I have accounts at about a dozen social media sites. From Facebook to StumbleUpon to LinkedIn, I have tried to keep my usernames consistent just for simplicity reasons. If you are a social media junkie, a marketing professional or just a geek like me and you want to have accounts on all of them and keep the same username for all, you can go to each site individually and see if your username is available.
Check multiple Social Media Sites
I was directed to a website called Username Check that you can check over a hundred social media sites at once. You can see if your name is taken and if not, you can directly through the link to sign up a new account protecting your username on popular social media sites.