I don't do client work anymore, but I do occasionally help out friends and neato people when they need design work done. The guys at KnowEm are some of these neato people. In a nutshell, their website allows you to check your username on a megabuttcrapton of websites at once so you don't have to manually check each one. Last fall I helped them build the interface for their site, and a few weeks ago I helped again when they needed an upgrade.

KnowEm puts hair on your knuckles and lets you check your username.

By default it'll only search the most popular sites, but if you click on social networks it'll let you search across hundreds. You can also check domain availability with it.

For example: let's suppose some greedy oatmeal-stealing bastards like Quaker, Inc. wanted to own the name "Oatmeal" on a ton of websites like Twitter and Facebook, this tool would allow yours truly to beat them to the punch. Ultimately it allows The Oatmeal to be stronger, faster, and more aerodynamic than ever, which then allows The Oatmeal to be more attractive to women and eventually park his lunar manship into their love nebula.
And by park I mean sexify! And by love nebula I mean vagina!

Update: Their website is experiencing some issues due to ten bazillion Oatmeal fans all trying to use it at the same time. If it's not responsive, please check back in a little while.