Bejeweled is a simple but challenging game. It's available to play for free here
If you haven't played before, the concept is simple. You line up three or more of the same jewel in a row, horizontally or vertically, by moving one jewel at a time. You can move any jewel horizontally or vertically (but not diagonally) one space, providing that move will combine three matching jewels. Simple, but addictive. It involves strategy, as you also want to keep lining up more moves. If you can line up four or five in a row, you'll get a flaming version of one of the jewels. Line it up with at least two more and it will blow up every jewel in the surrounding squares, giving you massive points and clearing a chunk of the level. Some of the ones you get from connecting three across and
three down simultaneously will clear the whole board for you. The first level is pretty easy, but as you progress, you can paint yourself into a corner and have no moves left. You won't be frustrated, wondering, either, as the game will tell you in no uncertain terms that you have no moves left. Then you just have to start a new game.
There's a progress bar along the bottom that tells you how much of that level you've completed. Though there's no way to save a game, there's also no time limit on the free, "Classic" version of the game so you can let it sit in the background while you browse the web, answer email, fix dinner, etc.
It's really an easy game, yet it is a good workout for your brain and works your hand-eye coordination to keep going, and it's pretty addictive.