I just got a Nook Color last night. I'd say getting a cover is pretty important. I got this one and like it:
http://gifts.barnesandnoble.com/Indu...?cds2Pid=35616
And maybe some sort of screen protector. I'm trying a clear one right on my Nook Color right now. I use an anti-glare screen protector on my iPhone and I like it because I almost never have to wipe fingerprints off it. I almost went with one for my Nook, but then I decided to try a clear one because, at least in the case of my iPhone, the anti-glare protector impacts the clarity of the screen just a little bit.
So far the clear protector is working out well, though I have to angle the Nook so I don't see so many reflections in the screen.