Here are some outstanding resources online that I highly recommend and are definitely worth your time:

Bicycle Safety: How To Not Get Hit By Cars
http://bicyclesafe.com/

Team Estrogen Bicycle Forums (for you ladies out there)
http://forums.teamestrogen.com/

The Bicycle Tutor (great how-to videos)
http://bicycletutor.com/

Bike Commute Tips Blog
http://bikecommutetips.blogspot.com/

Bike Forums
http://www.bikeforums.net/index.php