For those who like geography and for those who don't; surely someone must learn the capitals for their studies or simply wants to learn them. With Contest of the capitals you can review all the capitals of the world.
The game is very tailored while having a pretty cool design (Except for the small advertising banner at the top of the screen; personally I can't stand them). But like everything free can have drawbacks, here they come: we have to wait for the time we have to answer to tell us if we have answered correctly or not, which turns a game that could be exaggeratedly fast and fun into one a bit boring (hopefully updates). In addition, the Spanish translation is not very good (from an online translator, I would say).
Also, if you want to bite with a colleague to see who knows more capitals, allows you to export your scores via Facebook, Twitter and E-mail.