Almost a hobby within the hobby is surfing the R/C related bulletin boards and message boards. You'll find a wealth of information from a wide variety of modelers from all over the world on these sites. I've included a link or two to some of my favorites below.
R/C Related Bulletin Boards
The Hobby Forum (Includes a nice photo forum)
Paul Burke's website is full of useful building tips. If you're a Sig Kadet fan, you'll love this site....
PJB's Seriously Aeronautical Stuff
Great site for all things R/C but especially the flying aspect of the hobby..
Moorman's Aircraft Works
Howard Sullivans site contains just about anything a beginner needs to know to get started. Also contains some excellent tips and projects for any experience level
Howard Sullivan's RC Flight Unlimited
Hobby Related businesses
Mick Reeves Scale Models
The Hobby Stop
Ralph Saxton Scale Models
Bill Fulmer's Custom Cut Graphics
Bob Holman Plans
National Hobby Supply
Nick Ziroli Plans
Dave Platt Models
B&B Specialties Giant Scale Supplies
R/C Flying Club websites
The Fayette Flyers R/C Flying Club
Talladega Radio Control Club, Inc.
Atlanta Radio Control Club
Blue Max R/C club in Chicagoland
Personal websites of other RCers
Joe Huntley's B-25 page