Both the D and G lens series have full compatibility with the current Nikon DSLR range and there are some bargains out there in the older lens market, but I would advise that if you get them, that they are from a reputable dealer, so that any problems can be sorted out. There is a chart available from Nikon to show compatibility, but I am a bit busy doing the Sailor's Hornpipe on my desk at present. Why?
Todays good (unbelievable!) news is that I have just had a phone call telling me that my Nikon 18-200VR lens is in stock. I pick it up this afternoon and am looking forward to this one. If you are reading this Mark, I will report back when I have done a few shots with it. It has been a long wait...
Conan
Edit with late news: The Nikon D80 is out of the bag. Brief synopsis here -
http://www.dpreview.com/articles/nikond80/