There is also:
FTW - For The Win (something you think is uber-awesome; LotR ftw!)
AIR - Laughing so hard that you can't breath, may also be written with additional I's and R's for enhanced effect
PWN - Something that "owns"; totally rocks and is better than everything else
PWNAGE - Same as above but even better
Those are the "clean" ones I could think of at the moment
