There is a popular German game board and card games site, http://www.brettspielwelt.de/Spiele/
(available in English). I used to play some games there and it seem like a rich picking ground for next AI challenge.
Specifically, there'a a card game named Tichu and a board game named Dog. What makes them interesting even more is that you play in teams (2 x 2), even though you are not explicitly allowed to communicate with your partner. I think teamplay would be interesting to program.
Tichu ("Swiss-Chinese trick taking poker game. Beware, highly addictive."):http://www.brettspielwelt.de/Spiele/Tichu/
Also there are other games, for example:
6nimmt ("A point here, a point there - and a lot of bull in between.")http://www.brettspielwelt.de/Spiele/6nimmt/