The best free online games I’ve found are at  http://casino-games.pogo.com/, where there’s a huge selection for any taste. This site even offers prizes to winners without requiring a buy-in at all. The casino game selection includes slots, table games and poker.

The popular games are Turbo 21 and Vaults of Atlantis Slots. Turbo 21 requires that you play four hands at the same time, while trying to make each hand add up to 21. The faster you play the game the higher your score. Special features include Black Jack Express (you play against a clock), Big Payout (extra points for making 13 combos of 21), and Bonus Game (as many 21’s as you can make in 30 seconds).

Vaults of Atlantis Slots is a multi-line slot that takes you through undersea adventures as Tex Carter searches for the most legendary treasure in history. This game also has a chat option available.