Thanks to Creative Applications blog (definitely worth keeping up with if you're interested in browser, desktop, Processing, and iPhone-based art of the more fringe and digital varieties), I've discovered the lovely iPhone / iPod Touch app maker Rhizomatiks - specifically, their fantastic clocks.
At present, the Japanese artist collective has 12 free clocks apps available in the App Store. Each one has a different spin on telling the time. Clock10, for example, shows the time as virtual electronics knobs, while the recent Clock12 has a timely snowfall theme. Each Clock is elegantly minimal, and they don't take up much space (perhaps upwards of 10 MB for the whole set); personally, I've set up a separate app page for all of them, app glutton that I am.