Nagios sits quietly on a system, monitoring host resources and network services in order to notify the admin as soon as a problem arises. Indispensable.
License: GPL v2
Since becoming the default revision control system for the kernel, Git has become massively popular and easier than ever thanks to sites like Github.
Gimp is one of those pieces of free software that almost everybody has heard of. It comes as standard on many distributions, books have been written about it and it's often introduced as the free alternative to Adobe's Photoshop. But what's so special about it?
Aside from having such a silly, although memorable, name, there are three features that set Gimp apart. Firstly, it has a very robust set of tools, providing support for everything from sub-pixel sampling and custom brushes for painting, right through to advanced manipulation tools such as layers, channels and transformable paths.
Secondly, it has a versatile plug-in and extension system. This allows almost any task to be automated via a simple script that, once written, is easily executable by most users.
Thirdly, and most importantly, it has an active community of developers. This means that, even where Gimp lacks important features, work is constantly ongoing to extend it and make it the best tool possible. Developers have begun making real progress integrating these much needed features - even if it has taken a few years to get there!
License: GPL v2
Here at LXF, we're constantly testing out new distributions, experimenting with new server software or just messing around with different desktop environments. Of course, we don't like to mess up our carefully constructed primary systems so we make extensive use of VirtualBox.
Thanks to its guest additions package, it's well integrated to the host system and extremely fast. What's more, it also makes it incredibly simple to spin-up a new virtual machine with its GUI and there's command line and remote configuration tools as well.
30. World of Goo
A physics-based construction and puzzle game that's become widely regarded as one of the best indie games of the past decade.
It features beautifully drawn, cartoonish graphics that are cheerful, uplifting and timeless. All it involves is dragging Goos together to form a structure, but it's addictive and lots of fun.
31. Money Dance
MoneyDance makes staying on top of your finances extremely easy, providing a clear overview of upcoming bills, the status of various budgets (which it helps you to create) and informative graphs and reports. What's more, it can import account files from all major software packages and many UK banks.
32. Eclipse IDE
License: Eclipse Public
Eclipse is an excellent, stable IDE. Its Content Assist feature, which can auto-complete methods, types and fields, is excellent for forgetful coders or those working on complex codebases.
It also has features, such as automatically enforced coding styles and copy and paste traces, that make it perfect for team development.
Tomboy is a super little tool for collecting and organising your notes. Its support for basic formatting is useful and automatic saving is great. What really sets this tool apart, however, is how easy it is to link notes. This makes managing to-do lists or organising research notes on a complex project dead-simple.
The American National Security Agency needed an OS it could trust, so it decided to create a set of patches for Linux that would provide mandatory access control.
Since Linux 2.6, it's been integrated into the kernel and can be configured to restrict resources available to users, programs and daemons very effectively.
License: GPL v3
Deja-Dup is an extremely simple tool for carrying out backups the right way: automatically and off-site. The interface consists of two buttons, configuration details are straightforward and it supports a great range of backup locations including Amazon S3, SSH and Windows Shares. The perfect tool for reluctant backup-ers.
When we asked readers of TuxRadar what their favourite applications were, we couldn't help but notice that web browsers were cropping up in every category. No other application (except Emacs, perhaps) lets you do so many different things and, in many cases, do it better than you can in any other application.
With this flexibility in mind, we had to include a browser in our list of the best apps. The real question is why Google Chrome?
Well, for starters there's the interface. It does its absolute best to get out of your way: there's no menu bar, no status bar and the tabs have been integrated into the title bar. This means that the content, the stuff you really care about, can occupy more of your attention than ever before.
Then there's the fact that it continues to feel as though it's the fastest of all the major browsers - even after Firefox 4's release. Most of all, however, we think Chrome deserves recognition for once again reigniting the browser wars.
All the previous battles - first between Microsoft and Netscape, then Microsoft and Mozilla - resulted in the web getting better for all of us. Now it's happening all over again: Chrome's focus on speed, security and content has challenged all the other browser creators to up their game.
37. Ubuntu Software Centre
Goes some way towards making Linux repositories as pleasant as all those trendy 'app' stores that have appeared recently.
38. Amnesia The Dark Descent
You might want to turn on the lights for this one - Amnesia is perhaps the scariest survival horror game ever to have been made.
Creates traditional, hand-drawn animations. Create both bitmap and vector images, and finished animations can be exported as PNG or Flash.
When you're stuck on the command line and need to get help, Irssi should always be your first port of call. It's not called the 'client of the future' for nothing...
License: GPL v3
Not only is it one of the most popular text editors around, it's also a mail and news reader, project planner, calendar and much, much more.
License: GPL v2
An off-line thesaurus based on WordNet. It can look up selected text at the press of a button and provides synonyms, antonyms, causes and much more.
Banshee is an excellent media player in its own right, with support for audio and video in just about any format thanks to its GStreamer backend. It's also beautiful, with plenty of space given over to displaying album artwork.
What makes Banshee special, however, is its integration with Amazon's MP3 store and great support for all kinds of portable devices. The perfect all-in-one media solution.
License: GPL v2
As we've seen elsewhere, there are plenty of modern, beautiful and enjoyable games available for Linux these days; but for those of us who grew up playing the SNES, nothing will quite match up.
Thankfully, there's ZSNES available for Linux. It's an excellent emulator that will effortlessly run all your favourite games, from Mario to Street Fighter to Final Fantasy - it's got everything you need to lose yourself in an afternoon of nostalgia.
Keeping in touch is really important but it can be difficult when different groups of friends decide to use different networks to keep up-to-date. Fortunately, there's Empathy which will let you talk on instant messenger with your friends no matter what platform they choose to use.
It also supports a range of more advanced features on many networks, including voice and video calling, file transfers and conversation logging.
Shotwell is a super stable, feature-rich photo manager. Your collection of images is automatically organised by date but you can also use search tags, making it simple to find all the photos of person x or place y.
Shotwell's handy tools also make it easy to remove red-eye, crop, and adjust the colour levels in your photographs and the software also supports uploading your pictures to plenty of online services, including Facebook, Flickr and Picasa.
Tor defends you from traffic analysis, a form of network surveillance that allows thirdparties to build up a detailed picture of your online habits. It encrypts your network traffic and routes it through a random set of other computers to obscure the origin and destination from prying eyes.
While widely renowned for its usefulness to activists in oppressive regimes, Tor is also used by multinational investment banks, journalists and parents.
48. Music Player Daemon
Music Player Daemon - better known as MPD - is a server-side application for playing music. It sounds like a strange idea, but it actually makes for a very flexible, powerful product.
As a music player, it's very capable, supporting gapless playback and filesystem monitoring; as a server, it lets you do all of this remotely, whether on your local network, across the internet or from your mobile phone. Very cool, so long as you have a good client.
License: GPL v2 or later
The internet has given us access to an amazing repository of music and movies, with just about everything ever recorded made available in one place or another.
The problem is, it all comes in so many different formats: there's MP3s and MP4s, H264, OGG Theora, OGG Vorbis, WMA, WMV and MKV, among many others - it's enough to make your head spin! Fortunately, there's the VLC Media Player (affectionately known as VLC).
It's extremely lightweight and sports a no-nonsense interface, designed to get out of your way so that you can get on with watching your movies or listening to the latest episode of TuxRadar.
More importantly, however, it has built-in support for almost every format known to man (with the exception of DVDs, which require you to install libdvdcss). This means there's no need to research and install dozens of plugins, hoping you've finally found the right one for the file you want to play.
VLC's available for all the major distributions (although some will require you to do it through third-party repositories because of licensing concerns), and since you only need to install a single package, it's very easy to install. So, if you don't already have it installed, what are you waiting for?
50. Clockwork Man
The hidden object game is a classic genre that's remained popular throughout the history of computer gaming. At its heart, the premise has always been very simple: you move from scene to scene, at each of which you're given a list of objects that you have to pick out from the intricate backgrounds.
Usually, the scenes are connected by a story that develops as you progress through the game. The Clockwork Man doesn't vary much from this standard formula, but it's exceptionally well executed.
You join Miranda Calomy, a brilliant young woman whose university plans are interrupted when she receives a letter from her grandfather. From here the adventure begins and you set off on a journey that will take you through many locations in this alternate Victorian universe.
The backgrounds are hand-drawn, beautiful and immensely detailed. What's more, most either zoom or scroll giving you far more to explore than a single screen's worth.
It's not as frustrating as some hidden object games can be, thanks to your companion robot who can help you to find some of the objects. If you've never experienced this genre before, give this a try: it's got an engaging story, beautiful artwork and challenging puzzles too.