The International Association for the Study of Dreams
http://www.asdreams.org/index.htm

Tons of great information from researchers, including a giant list of nearly every book on dreaming out there.

http://www.asdreams.org/subidxedubookbib.htm

They have some nice FAQs with answers based on current knowledge and science:

http://www.asdreams.org/subidxeduq_and_a.htm