This is probably not of interest to anyone but my friends, fans (both of them), and inquisitive HR people. Enjoy!
Facebook: Chris Mahan. I only "Friend" real-life friends, though.
Twitter: chris_mahan.
Stackoverflow: Christopher Mahan.
Google Buzz: No.
Plaxo: No. Deleted my account.
Friendfeed: No more. Deleted my account.
Linkedin: Christopher Mahan. Useless though.