The latest edition of Nelson’s Illustrated Guide to Religions by James Beverley is an excellent resource. Unlike a lot of world religion reference books, this one, as the title suggests, contains many pictures, which are very helpful in picturing how a religion is practiced.
I also liked the charts and tables presented in the book. There was a lot of good comparative information on different divisions within religions/denominations, including date of formation and total number of followers.
Another useful aspect are the website addresses given for more information on religions. Some are official websites run by the different denomination or religion, some are unofficial websites (even some that I am sure that members of a particular religion would *not* want people reading!), but they all provide the reader with a starting point for further research.
The only thing I didn’t care for about this particular edition was it’s tendency to focus on some of the more “fringe” aspects of particular religions. One such example is the section on Kabbalah–to some extent, I understand this, because it is culturally relevant, and I’m sure people are looking for information on it, but a shorter description would have been adequate.
This is a great book to keep at home for when you have questions about a religion, or are trying to remember something you learned in the past!