My kids have a time limit on the computer, but we have soooo many excuses why we can't get off when it's time -- the timer stopped, I forgot to set it, I'm not done yet, etc. After throwing away two El Cheapo wind-up Sunbeam kitchen timers, we discovered this: yTimer, a free, junk-free download from Spacejock.com. This is great! yTimer has solved the broken timer problem!
With yTimer, you enter the amount of time 'til the bell (minutes, hours, or days), leave yourself a note reminding you what the timer's for, then blog or play away. When your time's up, a nice loud, schoolish-sounding bell sounds (you can adjust the volume), then a little window pops up with your reminder. There are forty different simultaneous countdown timers, so you can set it to remind you to make a phone call at 8:00 a.m., stop your kids' blogging time (not yours, of course!), or even check your eBay auction! It's pretty neat. We like it. (I especially like that eBay reminder feature, because I am so good at forgetting to bid at the last minute!)
Click on the link above, then click on the "download" link on the left. It's a small file and a simple set-up.