Hmmmm that is a good idea
....but we must also be sure that the game is large and simple enough for everyone to take part....
and initially, the input will be slow butwhen it catches on it'll be a hit!
How about this: similar to an everyday poll, a picture of a famous place or landmark can be posted on one thread by an admin or mod....anyone who logs on or sees the thread has to guess the name of the place.....and they can be allowed to guess once only.....if the answer is right they can get some points or maybe a plus rep
this is just a simple idea....but i believe it might work