Encyclopedia of ReligionsEnki
1.0 Varies with device
This Encyclopedia is packed with all the major religions/sects of the world and their numerous denominations. Each religion and denomination has a multitude of information about it including beliefs, history, practices etc.
You can either browse by drilling through the religions and their denominations, alphabetically or by searching. Also if you just fancy picking one at random just to pass the time you can do that too.