5th Chair

The Fifth Chair Foundation defines itself as "a not-for-profit organization that fosters online bridge education". The site is impressive, with a whole lot of various resources for newbies of all skills levels (from complete beginner dummy to world class novice and beyond).
In the Bridge School section you can find a well-structured intro to bidding (SAYC-based, I think) in the form of separate lessons, which are very newbie-friendly and with just the right dose of humour.
The more convenient pdf's of back-issues are in the Archive section here. The main headings are:

• Bidding
• Conventions
• Defense
• Declarer Play
• System Notes
• Miscellaneous

The Bookshelf contains a list of books that are suitable for different beginner levels; no reviews are provided but you can easily get them on Amazon, or just ask about on BBO.
Btw, I absolutely love their definition of players' levels:

B - Beginners (duh, what's a bid?)
N - Novices (I know just enough to get into serious trouble.)
I - Intermediate (Hooked and getting serious about this game.)
A - Advanced (If you've reached this level, you know it.)
E - Expert (If you've reached this level, your opponents know it.)
P - Professional (If you've reached this level, the bridge world knows it.)

There is a small but nice Links section as well as a glossary of the most common bridge terms in the Bridge Jargon section.
Overall, liked the site a lot!