Promote your brand on different social networking and social bookmarking sites by using related username. You can check the username availability for Linkedin, Stumbleupon, Flickr and many more by using a single service named Namechk.
Namechk is a free online service where you need to put the desired username and then it will show you whether that is available in social networking sites and bookmarking sites. I checked for a username “goodsay” and found the below result,
One can use this service to check for their brand name as username whether that is available for use on the social networking sites