11. Air Sharing Pro (£3.99)
Dropbox is great for a free document-syncing app, but if you want to turn your device into a storage drive, Air Sharing Pro is the way to go. The interface is vaguely Finder-like, and a number of file-types can be viewed within the app.
12. Photogene (£1.19)
It won't win any beauty contests, but Photogene is a fine app for quickfire edits to photos and images. You get tools to crop, rotate and fiddle with levels, and there are also built-in filters, frames and speech balloons for added image personalisation.
13. Weightbot (£1.19)
If you're keeping trim, regularly inputting your weight into an app may fill you with dread. Weightbot makes the process fun, with an interface full of character. It's no slouch in terms of functionality either: you get graphs aplenty, and there's even Withings scales integration.
14. Hipstamatic (£1.19)
Hipstamatic aims to bring character to digital snaps by aping the output of film cameras. You get a bunch of lenses and film stocks, which can be mixed and matched, and more are available via in-app purchase. The interface is suitably tactile, and although output seems artificially slow, Hipstamatic is fun and produces great images.
15. GoodReader for iPhone (£0.59)
Although iBooks has evolved to embrace PDF, leading iOS PDF viewer GoodReader continues to evolve too. For 59p, you get a first-rate app for reading PDFs, but it also supports Office files, images, HTML and text documents, and it integrates with Dropbox, Google Docs, iDisk, WebDAV and FTP.
16. Things (£5.99)
The App Store boasts plenty of to-do managers, but Things takes you further than most, offering an intuitive but powerful scheduling workflow. If you're a Mac user, Things also wirelessly syncs with the desktop version.
17. RunKeeper Pro (£5.99)
Forget Nike+, because RunKeeper Pro is where it's at for iOS fitness. The app uses your iPhone's GPS to track workouts, but you can also input sessions manually (for example, when using exercise bikes). Audio cues and customisable training sessions should appeal to pros, and iPod playlist integration and the in-app camera should appeal to all.
18. UK Train Times (£4.99)
Formerly National Rail, UK Train Times provides a user-friendly, efficient way to access up-to-the-minute train time information. Delays and cancellations are displayed, live departures are accessible, and you can tap 'next train home' to save you the hassle of a manual search.
19. WolframAlpha (£1.19, universal)
Now it's no longer priced quite so ambitiously (it launched at £29.99), you've no excuse to not buy WolframAlpha. The app is a contextual search engine, which aims to provide answers to questions rather than a slew of links. Often, it works brilliantly, and it's regularly fascinating to experiment with.
20. TomTom UK & Ireland (£42.99)
Given that it's a hugely popular manufacturer of standalone sat-nav units, it should come as no surprise that TomTom is similarly popular on iPhone; the iOS app boasts a high-quality, usable interface, plenty of options, and handy iPod app integration.
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