So, yeah, basically what the title says. I'll start off by leaving two titles, their ratings, pros & cons, and my status on the game.

Title: WonderKing
Status: Currently Not Playing
Rating: 8.4/10
Pros: Captivating, easy-to-play, free to play, customizable avatars, great advancing classes/variety of classes, special events, anime-ish characters.
Cons: Doesn't work in Europe, long download time, becomes repetative after a while.

Title: League Of Legends
Status: Currently Playing
Rating: 9.6/10
Pros: Non-repetative gameplay, free to play, unlockable characters, in-games emoticons, purchasable variety of skins, selectable arenas, 4-5 varieties of gameplay, playing rewards, characters are released frequently.
Cons: Long download time, occassionally laggy network connection.

So that's the basic idea. Just post any online MMO titles, their pros, cons, and your rating.