I've made a holder for my N800 from a cork sanding block which cost me 50p from a local DIY store. The block neatly slides into a storage compartment just above my radio.
What I did was measure the distance from the back of the N800 to the stand when open. I then used a saw to cut a slot for the metal stand to slide into, and then painted the block black to camoflage it a bit

Photos are here
http://picasaweb.google.co.uk/lh/pho...3Wik1yfndZem3w

http://picasaweb.google.co.uk/lh/pho...oHs39ikwviAx1Q