What are the best games online in the internet ( a game for macs)?

I'm looking for lots of games but Im not really getting interested. If you got any online games like toontown or something I'll take it.

Where can I download free games that are compatible with Macs?

I want to download free game trials, but they are ALL only compatible with Windows and I have a Mac.
What are some websites I coud use that have the same games but are compatible with Macs?
So far I have only tried Pogo and Yahoo! Games.