In classic Web 2.0 fashion, it's dropped a couple of letters from its name, but it does exactly what you think it does.
Just type in your preferred username, and it checks 84 different online services, sites, and communities to see if that name is available.

It works well as far as I'm concerned, although I don't remember signing up for Squidoo. Is it possible there is another myklbee out there?
Credit to WebWare, which is apparently now a CNET property. Who knew?
