Like Teach8, only casino game I have played on Facebook is Lucky Cruise. Lucky Cruise has a contract with WMS Gaming, so the casino games are exactly like the ones you would actually find in a casino. Some small differences in the way the bonus rounds play out, but overall good graphics and sound.
I NEVER buy chips. You get a certain amount of chips for FREE every 4 hours, and if you play certain games (Jewels Of The Night is a good example), they have good bonus rounds that will build up your level of chips.
So far, I have seen and played Game of Dragons, Zeus, Reel Em In, King Of Africa, Life of Luxury, Palace of Riches. As time goes on, I expect Lucky Cruise and WMS to add more to the lineup.