UltraChron Stopwatch & Timer
If you're looking for a simple, powerful, intuitive, and reliable stopwatch/timer app, Ultrachron is it. Ultrachron ($1 full version; free Lite version) manages to be both intuitive and feature-rich.
At the bottom of the main screen are two buttons, Stopwatch and Timer, so you can easily jump from one mode to the other (you can run a timer and use the stopwatch at the same time). The Stopwatch screen is simple, with a large digital display at the top, and Start/Stop and Reset buttons right beneath it. Once the clock starts, the Reset button turns into a Lap button. Hit Lap and it will record and instantly display lap times in a list. It will also announce the split time out loud ("Lap time: 34.6 seconds").
Once the timed event is complete, you can e-mail the entire set of data to yourself. At any time, you can click to name the item you're timing, which is very useful because the full version of Ultrachron archives all of the timing data it records. One of my favorite features in the full version is the ability to use the volume rocker to start/stop and mark laps. This keeps the screen clear and makes you feel as though you're holding a real stopwatch.
The countdown Timer is similarly intuitive. You can set the timing duration manually or by voice (in the latter case, you'd hit the voice button and say something like "5 minutes, 42 seconds"). If you have Speech turned on, your phone will call out time at various intervals, with increasing frequency toward the end.
Switch away from the app while the timer is running, and it will continue to show you how many minutes are left in the notification bar. Details like that set Ultrachron apart from other timer apps. Once time runs out, the app continues counting time in the other direction, so you'll know exactly how long ago the timer expired. The full version allows for a wide array of ringtone notifications. You can also choose a display color.
The only negative I can think of is a minor one: In stopwatch mode, Ultrachron measures down to tenths of a second, whereas most physical stopwatches would measure down to the hundredth. It's almost certainly a nonissue for anyone who using a phone as a stopwatch, but the added accuracy of measurement would have been nice.
Ultrachron is firmly entrenched on my list of must-have apps for Android. The free Lite version is fantastic, but for $1 you get some great extra features. I'd pay $1 just to support the developer.