Taiwan, right?
I've been taking an increased interest in unrecognized states in recent months. Taiwan is the really weird one. It seems indisputable that it's a functioning nation-state, and yet it doesn't get recognized because of the political dick-waving that China loves to do.
Somaliland as well, actually. There you have a reasonably functional country which isn't recognized by anyone because Somalia is still a member of the Arab League, despite not having any functioning structure or control over it's territory.