I don't know much about Asatru. I can speak only on Paganism with a Wicca/Witchcraft bias. For that I recommend the authors Penczak, Starhawk, Lipp, De Grandis, Cunningham, and Ted Andrews.
Drawing Down the Moon by Margot Adler is a little dated, but otherwise an excellent book.
There is also a brilliant book by an anthropologist, Tanya Luhrmann, about paganism and magic in contemporary London. It's called Persuasions of the Witch's Craft. Academic, but very well written and provides a keen insight into pagan spirituality from an outsider's point of view.
answer: Drawing Down the Moon by Margot Adler gives a good overview on different pagan traditions - it's a little dated (especially on the Asatru section) but still good.
Asatru - Teutonic Religion by Kveldulf Gundarsson
Our Troth ed. K. Gundarsson
Essential Asatru by Diana Paxson (a good basic primer)
Poetic Edda - trans. Bellows or Hollander
Prose Edda - trans. Bellows
Some books on Paganism & Asatru?
