We picked up this card game on sale at a Go! Games and Toys in the mall after last Christmas.
It's as simple as can be: just a deck of cards and some very brief instructions. Each player selects one of four categories and another player reads the selected question off the top card. The first person to get two right in every category wins (you need to keep track on a piece of paper, not provided). It serves as many players as are willing to sit around the table with you.
So this is more suited to casual trivia and chatter, not fierce competition. Sort of the way some groups play Trivial Pursuit without the board, just reading questions for the fun of it. We definitely enjoyed it, and even learned a little.