I like Zombie Dice, and it's fun, easy, and portable. It's definitely a lightweight casual dice game though - there aren't a lot of real choices to make, and you have to wait for everyone else to take a turn so there's a little downtime. The game is quick enough so there's not that much downtime, of course. Martian Dice gives you the same sort of thing. Dungeon Roll is something else in the same vein - multiplayer solitaire, very light, simple choices in a cute theme in a neat container.
However if you want something with a little more meat, I'd suggest you check out my game Ninja Dice. Full disclosure that I'm the designer! I made Ninja Dice to plug a few of those issues mentioned above. ND is fully interactive (you don't wait for a turn, everybody is usually playing); there's a bit more strategy involved; and there's a unique mechanism in play where the dice location/orientation after they fall are part of the game. Plus it comes in an adorable plushie Ninja head/dice bag thing. ND is kind of a "medium" casual dice game. We just released it and I had a blast playing with folks at PAX East last weekend.
But, if you are looking for something in the "light" casual dice game family with games running very quick and very easy, Zombie Dice is definitely something you should check out. It's fun and easy to pick up and available pretty much everywhere that sells games.