I was recently played with some websites that allow you to look-up your commonly used username on many social networks. One for example, will let you check your username availability across 120 different social media sites and for $64.95 they will create accounts for you at all of those sites.  I am one less inclined to pay the money, so to save you a few minute you can download a bookmarks file that will help you quickly open the sign up page to all 120 sites that knowem.com currently checks.

• Firefox (download this .html file, import the HTML into your bookmarks, then open all in tabs)
• Safari (unzip this file, and just select all of the files and open them in Safari, make sure your default preference is to open new pages in tabs)