Nice book on Nikon DSLRs
I have a D70, D90, D200, and D300, and often have trouble keeping their different features straight. I recently ordered and received a very pleasant book that covers all DSLRs from the D1 to the D3s. I bought it through Amazon for $20, 6 by 8 inch paperback, 288 pages, very nicely illustrated. It is "Nikon DSLR System, the expanded guide", by Jon Sparks, published by Ammonite Press in 2010. It is small enough to fit in some system bags and has a wealth of information.