A card reader and a cable (USB or Firewire) for it, depending on what it uses
A LensPen (about $8)
You might also want to consider replacing the strap with something else -- either a neoprene neck strap or a hand strap or a sling, but this is optional.
Also, just as a FYI, you're not going to often see an authorized Nikon USA dealer sell a camera for more than about $100-$150 below the going rate by other Nikon USA dealers. So if you see a $600 "saving", that should set off all yer alarm bells in your head including the one that says "WALK AWAY PRONTO".
A list of authorized Nikon USA dealers can be found here:
http://www.nikonusa.com/fileuploads/pdfs/Authorized_Dealers/Nikon_AuthDealers.pdf
Buying from or through Amazon is generally safe. If you look closely, it will either say 'Sold by Amazon' (coming from Amazon themselves) or 'Sold by ' (coming from an Amazon partner, but not Amazon itself).
Amazon doesn't invite fraudulent dealers to participate in their affiliates program. So the dealers they use are generally reputable ones. But if you want to buy from the best online photo dealer in the world, that'd be B&H Photo and Video in Manhattan. Customer service is top notch.
Other major and reputable dealers would include Cameta, Adorama, J&R, just to name a few. I generally recommend buying from an actual camera store (whether online or in person) because their staff will be most familiar with cameras, the major manufacturers, dealing with after purchase issues, etc.
