Note: SITE DOES NOT ALLOW U.S. BASED PLAYERS.
This is a screenshot of a limit Hold'em game, for play money, at Pokerroom.
Texas Hold'em, Omaha, Seven-Card Stud
The best thing about Pokerroom.com is that you don't have to download anything to start playing, you can just pop up the Java window from any Web browser and start playing. This means that Mac users, Linux people, and PC people can all play here.
The software is very friendly and easy to use, and it's easy to take notes on players, and search for specific ones. Featuers also include chat and the ability to multi-table.
Players are given more time to make decisions here than at some other sites, so games can seem slow. But really, is 45 seconds that long?