Last week when I was at the desk with Barbara she recommended The Encyclopedia of Relgion to a student. It is a great tool for anyone wanting an anthropological perspective on religion and it covers some hard to find topics such as voodoo and santeria.
We have both the definitive first edition, edited by Mircea Eliade, in REF BL31 .E46 1987) and the new edition of 2005 at REF BL31 .E46 2005. The new edition is also available online in the Gale Virtual Library. It's worth checking both editions.