I recently bought a new card game, called Hanabi, and I strongly recommend it. At the time of writing this, you can get it for $10.42 on amazon. The thing that sets this aside from most card games is that it is completely cooperative. The thing that sets it aside from most cooperative games is that there is hidden information, so it is not just a single player game in disguise.
The basic idea is that 2 to 5 players each have a hand of 4 to 5 cards that they hold backwards. Each player can see all cards in other players hands, but not the cards in their own hands. Players take turns playing cards, discarding cards, or giving hints about other players’ cards. If you attempt to play an invalid card, you get a strike. In the end everyone’s score is the total number of valid cards played.
The game plays well for 2 to 5 players, but is rather difficult for 2 players. My wife and I got a perfect game on one of the easier difficulty levels, but have not yet done so on the hardest difficulty level. I am convinced that a sufficiently well designed convention can win almost always. So far the game has been a hit with everyone I have introduced it to, and a couple people decided to buy it after playing their first game.