I just ordered this rubberized skin to hold me over till a good one like the one I have from bodyglove for my G1 comes out. It was only 4 bucks shipped so if its terrible no big deal.
http://cgi.ebay.com/Black-Rubberized...item27acc4226e

And ordered this leather case which I think will work even with my skin on. It has a Magnetic closure but I guess that is OK since the N900 has no compass. 8 bucks delivered.
https://www.amazon.com/gp/product/B0...ss_T15_product

I was going to wait to buy the N900 till after the phone was out awhile so there would be more choices for cases, skins etc but $480.00 delivered from dell was too low to pass up.