User Name Check is an interesting free online tool that lets you find out whether an user name is already take or not in major social networking and other popular web sites. This tool is very useful for people who want to create accounts on multiple sites with same name.
Lets say you want to start a new blog and planning to create an account in DIGG, YouTube, Twitter and other popular sites to promote content of your blog and also to build a social network with other bloggers. Before choosing a name for your account, you can run a test on User Name Check to verify whether the particular username is available in the major social networks or not.
Would you like to know what APIs the tool uses to check availability of user names? Here is what the developer says
The site is simple. I have a stack of webapp urls, the application pings the site using the username you want to check, if it returns a "no user name" error we return that.
Hey developer you are a brilliant. You solved a complex development problem with a simple solution.
Where is Your Username Registered? [via life hacker]