Bridge and poker are my suggestions too. Also there are tarot card games that are pretty complex.
Yuuu gii ohhhhhhhh
Poker requires a lot of skill, plus you HAVE to play with money otherwise it's pretty moot.
If that's not your cup of tea and you want to find something different, you can try Biriba.
No Limit 2-7 Single Draw is a very skillfull game. It's structure opens up for extreme bluffs. As others have said Omaha hi/lo is also a very good form of poker, but it takes a long time to master for someone that has never played poker before.