I found the following ebooks very helpful when I started out with Nikon DSLR. Answers every basic question you might have about optimum camera operation and technique.
--The ebooks by Thom Hogan on DSLR and Flash:
http://www.bythom.com/ (great site if you shoot Nikon in general)
--The ebook by Peter Inova and Uwe Stenmueller, "DSLR: Nikon D70" (Inova does versions for other cameras as well)
These ebooks come with photoshop actions and other goodies, some of which I've used a lot.
I'm also a fairly frequent visitor to nikonians.org for tips, reviews, and news about the Nikon world.