I always appreciate tools that make my meditation practice easier in some way. I often use my digital watch as a timer when I meditate, but it takes a little while to set, especially if I don't meditate for the same period of time each day. The electronic beep ending my session is also a bit unpleasant.
Recently I have been using a very helpful tool my dad passed along in lieu of the watch timer. It consists of two mp3 files - one of 5 minutes of silence and one of a singing bowl chime. I've created a playlist in iTunes using these files with 3 segments of silence and 3 chimes, for 15 minutes of meditation ending in 3 bells. I can add more tracks of silence at the beginning to make my session longer, or select a later silence track to start on if I want to meditate for a shorter time. You could also burn the tracks to CD if that works better for you.
The only thing to watch out for is that your computer speakers are on and set at a suitable volume. I have gotten into the habit of playing the chime once or twice to adjust the volume before I start. You could also put a chime at the beginning of your playlist to begin your meditation that way, and it would also alert you if the volume were turned off or too loud.