American Contract Bridge League -- A huge site with resources for beginners through experts. Some interesting areas to check out include:
Ecats Bridge -- News on international tournaments, laws and appeals, plus a good selection of articles and other interesting bridge features. Maintained by Anna Gudge and Mark Newton of the U.K.
Standard American Yellow Card -- Detailed explanations of conventions used in the "SAYC" system, which is popular among players in online bridge clubs.
How to matchpoint -- A step-by-step guide from Baron Barclay Bridge Supplies on how to figure matchpoints from traveling score slips and interpret the results on recap sheets.
Duplicate movements -- from Baron Barclay. Also available are Alex Groner's instructions for setting up a rainbow individual movement.
Duplicate scoring chart
Online bridge clubs -- Links to Bridgebase Online and other clubs where you can play duplicate bridge on the Internet.
Worldbridgeclub.com -- A social network for bridge players who are looking for compatible partners for online play. The site also includes features for measuring your skill and improving your communication with your regular partners.
Bridge travel -- Links to online booking sites, tournament calendars, a North American club directory and other sites for traveling players.