Links
Here are some links I've found useful. Please do let me know if you know of other interesting sites.
Here are some web sites on chess in general - how to play, where to play:
FIDE, the World Chess Federation
The United States Chess Federation
Chess.com, where you can play other people from around the world online for free
Bruno's chess problem of the day
132 chess puzzles
Good sites on computer chess programs and utilities
Arena, a UCI engine GUI interface
Superchessengine, where you can download over a hundred UCI chess engines to try out
Some of the best rated UCI engines
The Computer-Chess wiki has hundreds of UCI engines to try out
WBEC-Ridderkerk, a great computer chess ranking web site, with engine downloads, rating lists and more.
CCRL (Computer Chess Rating Lists) website. Another great computer chess engine ranking web site.
Unfortunately, Ziggurat 0.18 ended up on the bottom of the CCRL rating list. I hope V 0.20 will improve that ranking, and future versions will continue that improvement.
Good sites on chess programming:
Dr. Robert Hyatt's (computer chess guru) home page
Computer chess news
A great wiki on chess programming