Adherents.com - all religions - good for answering common questions and providing some statistics
Patheos.com - provides information on all religions, as well as forums, communities, etc. - audience is anyone looking to learn more about different belief systems
Saints - info on over 7,000 Roman Catholic saints, venerables, etc.
Wabash Center's Internet Guide to Religion - provides links to many websites
Yahoo Directory: Religion and Spirituality