I'll try to add some useful links in researching denominational and cult doctrines here.
The best that I have found thus far must be the Catholic Encyclopedia. Sure it is Catholic, but it is thorough and easy to read. It is biased to the Catholic position, so you know where they stand on many issues. They appear to state all of the most important distinctions of one denomination from that denomination's viewpoint. Core beliefs of several key statistics are provided.