Over the past several years I have been studying Wicca. Mostly for personal insight and enlightenment. The study continues as always, but here are some great books to check out:
Drawing Down the Moon by Margot Adler
Maiden, Mother, Crone by D.J. Conway
Casting the Circle by Diane Stein
Spiral Dance by Starhawk
Also good reading is anything by Scott Cunningham.