Freeview
Freeview recently added a TV guide which allows you to scroll back and see what you've missed. Click on a show, and if it's available on catch-up, there will be a link. Press it and you're taken directly to the show. It's a neat way of pulling all the services together, but is only available in a browser.
4oD
4oD is an on-demand library of content from Channel 4's archive. Programmes are split into Collections so, for example, the Olivia Colman Collection has episodes of Peep Show, Bad Sugar and Comedy Lab. You'll need to register, but doing so allows you to create playlists, track shows, and keep a scrapbook of information.
TV.com
TV.com is only available in the US, but it offers full episodes of CBS shows such as How I Met Your Mother. It also allows you to review shows and share them with friends. You can also discuss programmes on its forums. The iOS app only shows highlights and clips from shows, but, if you're in the US, you can view full shows in the CBS app.
Demand 5
Demand 5 has a library full of crime dramas, made for TV movies and kids' programmes. And, of course, Channel 5's own inimitable style of documentary. It's a mix of recently broadcast stuff and on-demand content, though it's difficult to tell which is which. You can watch it in a browser on your Mac or using the iOS app.
NBC
The NBC website has full episodes of recently broadcast and archive material as long as you're in the US. It doesn't have the social features of TV.com, but you won't miss them if all you want to do is catch-up on shows you've missed. There's an iOS app too, which has full episodes of selected shows.
Watch live TV
Apps, add-ons and online services for a computer-based gogglebox
There is an abundance of ways to watch live television on either your Mac or iOS device. In addition, if you have an Apple TV, some iOS apps will allow you to mirror their output over AirPlay.
The 'traditional' way to watch live TV on a Mac is to use a TV tuner. These addons connect to your Mac by USB (early boxes used FireWire, but USB2 is fast enough) or to your iOS device using its Dock connector (Lightning devices are due soon). Most are no bigger than a USB stick, and in the case of iOS versions, smaller.
They come either with a built-in antenna or with a socket into which you plug an included aerial or your own set-top or roof antenna. Some even have two tuners so you can watch one channel while recording another, or combine them to optimise signal strength.
In the UK, only digital terrestrial and free-to-air satellite television are supported. In other countries, versions for paid-for satellite TV are also available. As with a TV tuner, the quality of the picture is dependent on the TV signal in your area; you may need a roof aerial to get the best from it.
If you're in a strong signal area, you can use a TV tuner with a laptop or mobile device and have the antenna magnetically fixed to the laptop, or as part of the tuner in the case of a mobile device, and watch TV live without any wires at all.
There are two vendors of TV tuners for the Mac and iOS devices, Elgato and Equinux, which uses the Tizi brand. Elgato has a USB-stick style tuner called EyeTV DTT and a significantly smaller model, barely bigger than the USB connector, called EyeTV DTT Micro. There's also a USB stick with two tuners, called EyeTV Diversity.
