I could swear someone asked this very same question only a few days ago ;).
It all depends on what type of games you like :).
For word games, I suggest BookWorm. TextTwist and WhatWord are decent, but I really like BookWorm. All can be found at
Astraware
For puzzle type games I have been playing DiamondMine (another Astraware game). Cropped Out and Egghead are basically DiamondMine knockoffs you can find at
Clickgamer . There are some other neat titles at Clickgamer worth checking out...like Toki Tori and Knight Lite.
As far as RPG/RTS games go there are lots of choices. Right now I am playing (
Hyperspace Delivery Boy ). Thanks Raynne for pointing me in that direction.
Age of Empires Gold Edition may seem a bit pricey at $29.95, but it is well worth the investment.
BugLord is another that is not to be missed. The other game I would recommend is
EverQuest.
I have a ton of games, but these are the ones that I am playing the most right now. Most of them have free trials/demos, too.