Self offers lots of in-app purchases, for sounds, and for a "Pro Timer," which lets you choose times other than the default 15, 30, 45 and 60 minute settings. You can export your meditation stats in CSV format to open with, say, Microsoft Excel, and you can share you meditations on Twitter.
Zenso Meditation Timer
Zenso Meditation Timer (free; iOS) has limited features, but is enough for many meditators. Choose a time, and choose intervals if you wish, then select from a number of bell sounds. The app displays a digital clock surrounded by an enso, a type of Japanese circle, which starts out all gray, and gets darker as time elapses.
I've been using the word "minimalist" a lot in this article, because the goal of many of these apps is to not distract you. Mind (free; iOS) is probably the most minimalist of all meditation timers. Swipe the rainbow bar to set a time, and then tap to start counting. Mind plays a gong when the time's up. That's all it does. It doesn't display time — which can be a bit of a problem, if you think you've been sitting a long time, and need to check — and there are no settings to choose a bell sound, which most other meditation timer apps let you do. However, the bell sound is nice, and if you just want to sit and not be bothered by anything other than a reminder when your time's up, this might be just what you need.
With all these choices, you'll find it easy to pick an app that suits you. Some are simple, and some offer more complex features, but all of them may help you keep a regular meditation practice without looking at your watch or your iPhone's clock to see how much time has passed.
Sign up for Computerworld eNewsletters.