Android: If you're looking for a snappy timer application that doesn't require a lot of fine motor skills and tweaking to use, Tick! is a super simple timer app with an easy to use rotary-style interface.
More than a few applications, timers included, suffer from GUI overload. When you've got a small screen and you're trying to use an application one handed and focus on something else (as you often are with a timer application) a simple interface is a must.
The interface is similar to a rotary phone or the click wheel of an iPod. Instead of tapping away at small buttons you rotate your finger around the circle to dial in the time and then tap the power button in the centre to start the timer. Tap and hold to pause the timer. It's simple and quite easy to use one-handed.
Tick! is a free download for Android devices. Search for "Tick!" in the Android Market or scan the QR code at right.