Occasionally there are new websites on RDA. Lately, there are not very many. The last one that I looked at and still follow is Colinandshort’s Resource Description and Access Happy Fun Time Companion. This site just keeps getting better and better!
Just recently, the Health Librarians of Canada got together and created a wiki dedicated to RDA. Unlike some other sites out there, they encourage people to sign up and participate on the wiki. Even if you don’t sign up, there’s some good general information on RDA.