The timex datalink -- a discontinued (as of 2010) PDA-watch
This watch is so awesome!
* It has a true 10 entry appointments book -- which means you can set the watch to go off at any time of the year, month, week, day. For example, you can set an alarm 6 months from now, with the message, "Change Oil".
* It has the old standard ironman lap memory. I actually have this constantly running, to time my "intervals" throughout the day, how much time I spend working, exercising, relaxing, etc.
* 5 alarms, separate from the appointment book.
* Notes! I use it for email addresses of people I meet, shopping lists, weird useful stuff like license plate numbers, reminders. Obviously you can't write a paper on here.
* Timers -- I use it mostly for tea or cooking
I really wish they would bring this watch back, or someone would make another version of this. I don't expect my watch to tell me the atmospheric pressure or the baraometer readings, but in 2010, I think I should be able to expect a watch to do arbitrary alarms. Also, the notes feature is surprisingly useful. For example, I was in a locker room yesterday, and took down somebody's email address.
In short, the most useful watch ever, assuming you want to do complex with your time.