Most of the games on Facebook are timesucking ad scams. They are improving some of worst offenders, but a chunk of the games aren't even fun. It's just collecting and asking other to give you their collected shit, by and large. Whatever works, I guess. Hidden among the dross is a true jewel* in the Facebook experience.
Game of the Day: BEJEWELED BLITZ
That link is for Facebook folks only, sadly. They don't host the game on their regular website, I think they are taking advantage of the backend of Facebook for stat tracking. There's an iPhone version too, but I'm not sure if that one also uses the Facebook connection.
The game mechanic is simple--a grid of jewels, you can swap them orthogonally one slot. Match three in a row, they explode and more fall in to replace them. You've got a minute to do as much damage as possible. There are power gems for match-4, hypercubes for match-5, and they just bolted on some bonus thingywhatsies in the last week or so to dress it up, but the core gameplay is still all about matching and clearing.
It's amazing how satisfying this can be. One minute is no big commitment, and when it goes right it just flies by. The game really nails the sweet spot of luck and skill as well. They have recently moved it a little to the luck side, but the skilled players still rise to the top week over week.
I should be invested in PopCap games--I can see three of their games on my the Dock as I write this. Do me a favor, check out their fine wares--you can do a lot worse.
* See what I did there?