I had to set up a few of these recently for work, and at the same time, I set one up for my username. More out of curiosity than vanity, you understand. I've got the same username on most of the websites I use, so I was interested to see where and when it might pop up.

Anyway, it has absolutely paid off, because I just got an email alerting me to the existence of my doppelganger:

http://w.plentyoffish.com/member13578019.htm