Misplace your cellphone? This single-purpose web site can help
If you don't happen to have a second phone handy, Where's My Cell Phone can help. The web site is covered with annoying ads, but it provides one marginally useful service. If you need to make your phone ring, all you have to do is enter your number and hit the "Make it Ring" button. Your phone should start ringing a few seconds later.
Once you place a call you have to wait a few minutes before making another, so make sure to spend the 30 seconds or so that you have while your phone rings wisely.