Justin March
Justin March reviewedNameChkSee if your username is available on 100+ social networks
 RecommendedPros: 

Checks username availability quickly, tells you what if anything is wrong with your idea. Social platforms are ordered by popularity.

Cons: 

Doesn't cover the range of platforms like its competitor Knowem.

Wish I could remember the URL NameChk seems instantly forgettable to me.