OKBridge - is a great way to play bridge online, learn more about the game and meet friends around the world. There is a membership fee and a free 7 day trial membership. OKB also offers tournaments, publications and a bridge reference. There are two ways to play bridge online at OKBridge:
Select 'Play Bridge' from the website. This method is great for those who do not have or are not comfortable with Windows.
Download the OKWin program and run the program from your computer. I prefer this method because it has more options.
The following independent bridge teachers (and many others) offer classes at OKBridge too:
e-Bridge - Play bridge online or watch major world tournaments. Play for free in their social room or use their paid service and play in multiple daily tournaments with ACBL masterpoints. Their VuGraph provides live and archived action at world tournaments with a commentator. There also are bridge articles and a bidding contest.
Bridge Forum International - Classes and bridge articles by world class bridge players. Try their monthly Bid with the Experts contest.
SA-YC Simplified - Excellent explanation of the sayc (Standard American Yellow Card) system plus other gadgets used mostly in 2/1 system.
GIB - Ginsberg's Intelligent Bridgeplayer is a bridge program that uses artificial intelligence. GIB is the only bridge robot to be successful against professional human bridge players and win ACBL master points. It plays a wide variety of systems and conventions. GIB robots used to play at OKBridge, but have not recently. I was very impressed with them there and purchased the program for my computer, however I'm somewhat disappointed in the bugs in the Windows version. The ACBL's Learn to Play Bridge software is included free on the GIB CD.