There are some sites, wich multiplayers games you can ebmed in your sites - come2play.com, and a few others you can see here
http://www.moreofit.com/similar-to/www.come2play.com/Top_10_Sites_Like_Come2play/

i have seen a dolphin site, where when you join in dolphin site, your are auto log in in the come2play sistem, and that was verry nice, and the users ware play in multiplayer. Does anyone of you have a idea how to do that ? There are some options like some kind of API, but thet tells how to see more do it manual for anyone user, and that would be terrable.