I can never seem to get past the "buy a marginally clever domain name" phase. So I can go down the list of my domains on GoDaddy:
Yakrazor.com: time management app. I can't remember exactly where I was going to go with it, but the basic idea was to bring some order to the process of Yak Shaving.
ToShove.com: provide a nice REST interface on top of Apple's push notification service.
CarZero.net: TSD rally site; mostly an online scorekeeping app. Still considering building this out with an iPhone-based front end.
SportsCarClub.net: basically WordPress for local car clubs, plus postal-code search for nearby events and clubs.
And then I have a half dozen more that I'm actually doing something with or seriously plan to do something with.