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So how do you know if your username is available on most social sites? You could try each site individually, or you could check 76 of them all at the same site with namechk.
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Just type a username into the namechk text field, and within seconds you'll see sites where your queried username is available in green, and sites where it's already taken in red.
There's not much more you can do with namechk, but it's certainly a handy tool for finding out where you can own your preferred username or vanity URL on the Web.
See Also: 25+ Ways to Manage Your Online Identity