Nikon has issued a recall for certain batteries used in the D100, D70, and D50...the battery has a flaw that may cause it to overheat and melt. Check the site for your battery's lot number to see if you're affected.
Several companies who manufacture digital cameras have issued "silent recalls" due to a faulty chip distorts photos when it fails. Sony, Canon, Nikon, Olympus, and others are affected.
Digital Photography Review has more; here's the Nikon D2H & D70 advisory. (A "silent recall" isn't an official recall...the companies are only repairing items in which the faulty chips fail.)
Update: Eliot sez: That's the wrong service advisory for Nikon...it's an unrelated problem. Here's the related advisory...doesn't affect any of their dSLRs.