This could be the best collection of:  Basic Bidding, Bidding Conventions, Competitive Bidding, Declarer Play, Defense, Practice Deals & Partnership Bidding Practice

A link of- all of the bridge conventions you can think of

Quick reference guide to every bidding convention  ever

This website will walk you through the process of filling out a convention card for duplicate bridge

You can fill out and print your own convention card

http://www.learn2playbridge.com/

The Fifth Chair Foundation is an international non-profit (tax-exempt in U.S.) organization dedicated to fostering bridge education on the internet and attracting new players to a game that has challenged, intrigued and entertained people since the early 16th Century when it was known as whist in England

designed for those interested in double dummy bridge problems, it's involved - and fascinating

Learn bridge! No Fear Bridge is the most fun way to learn bridge The website for learners.

The member's site is packed with online learning activities for bridge beginners, improvers and advancers.

The common game allows you to compare your bid and play with people playing in duplicate clubs around the U.S., Canada & Europe.  They will provide a full hand analysis of each hand played so you can see how you did against the best play of the hand, and also the rest of the common game players.  You can even write to the expects with your questions.  

Unit 141 web page. Information about all tournaments at Bala