Find if a user name has been already registered?

Recently i came across a site which can be used to check if a particular user name has been registered on all well known sites.

If one wants to have a username that can be used for almost all the popular sites without having to find themselves frustrated to see that their favourite username has gone up or find themselves forgetting the user names since having too many user names can jam one mind, one must definitely try this site.

The above picture is the screen shot about the availability of user names for my name.

Hope somebody finds this site to be useful.

For geeks:every site while checking for login appends the user name/a modified form of the user name in the search query in the address.Using this and by understanding the difference in the html structure of the page which represents successful authentication and the page which says username does not exist this kind of checking can be done(i think so.If somebody has any idea please let me know..)