If there's one thing Fiverr has done...
 

...it has made the owner of Fiver.com a happy person. Dude's probably getting thousands if not tens of thousands of visitors a day to his parked page just for owning the correctly-spelled version of what was not really much of a used term.

why "Fiver" is good keyword?

fiver is a MUCH used term in the English language as spoken in England . .

seems a bit foolish to start a website on a typo domain... not sure what the guy was thinking...