The creators of Hexic, Carbonated Games, have taken a wicked card game to the Xbox Live Arcade World, and I don't know about anyone else, but I am incredibly addicted. Released last May, UNO now has plenty of followers, multiple downloadable themed decks and it's a blast every time. The game features three different game modes including Standard UNO, Partner UNO, or House Rules UNO. In House Rules UNO you can customize the rules of the game to pretty much anything you want. On Xbox Live you can play with up to four players, but it's rarely less than that. It also supports Live Vision, which is great for adding to the conversation, which also adds to the fun. You'll meet a bunch of people with similar gaming interests and you can then play a retail game over Live later. It's always decently competitive, it's always fresh, and it's never boring.
UNO's only 400 points or free if you buy the Xbox Live Vision Camera, or enter a code with a 12 month expiry. Having the camera is optional, you can choose to use it or not, and view others or not even if you don't have one, your gamer picture will just take the place of your video spot. The themed decks range, most costing 100-200 points. Of course you can always listen to your own soundtrack, blow it to 1080i, and pull your ranks on the leader boards.
Overall it's just a fun card game with a range of people, and playing with friends is basically just like the MSN for gamers, hanging out around a card game and carrying a conversation. I've talked about everything from the weather, to UNO nudity, to the new demo coming out for Halo 3. Add me up and we'll duke it out UNO style. Be sure to call UNO before your second last card is played.