As social networking and other Web 2.0 sites proliferate, and as you begin getting involved more and more in them, your user name pretty much becomes your identity. If your user name gets used by someone else, it could be a big deal to you—particularly if it’s a branding ID like your real name or your product.

UserNameCheck.com checks a plethora of sites (currently 68) for the availability of your user name, then gives you either a link to signup (if available) or to view the user on the site. Use it not only to see how and where your user name is being used, but also to show the newest Web 2.0 sites you should be checking out.