A book that has been invaluable to me is The Allergy Self-Help Cookbook by Marjorie Hurt Jones, R.N. - it has detailed explanations of the different alternative flours and their uses. It's a book describing the Rotary Diversified Diet (for persons with multiple food allergies.)
We have used rice, teff, amaranth, and quinoa flours fairly successfully by combining them. The book helps explain which are good for browning, thickening and/or baking which helps alot. I checked it out of my local library to start with, and then bought it at Barnes and Noble after I saw it would be useful for us.
Edited to add a link to the book at Amazon:
http://tinyurl.com/4jz9lp