I have noticed one user on photo.stackexchange.com that has more than 100 in reputation but no answers and no questions - how is that possible?
Just to clear up gabrs answer.
If you have an account in any of the stackexchange websites with 200+ rep (Specifically StackExchange 2.0 websites that were created through Area51) if you login with that same id on another SE website, it will associate your account and give you +100 rep.
Quote from Jeff Atwoods Answer here "The feature is intended for experienced users who have already reached this threshold, and are now proceeding to new sites in the network.
That way they aren't "noobs" on the new site, they have 101 rep and can use all the core functions"