We're big fans of card games in our family. After all, you can typically play them quickly, so if you only have 15 or 20 minutes to play, you can still have fun. Also, they are super portable ... sometimes we take them with us to restaurants and play while we're waiting for our meal. (Obviously, we don't go to 5 star restaurants!)
I recently found a new card game at Target called "Hit the Deck" by the maker Fundex. It's been a real "hit" around our house. For those of you familiar with UNO, it has some of the same properties, which makes it easy to learn. Basically, if the person in front of you lays down a red 4, you can lay down any red card, or a 4 of any color. There are special cards that are different from UNO which really make the game lively and interesting. One such card, "Hit the Deck with your Hand" has everyone lunging to be the first to slap your hand down on the card.
This game is for 2 to 6 players, and has recommended age of 6+, which I feel is reasonable.
Overall, I think this is a great fun, inexpensive game for the whole family. Enjoy!