I have one of these blue egg-shaped readers that work fine with my N800...
http://cgi.ebay.com/USB-2-0-MINI-MIC...QQcmdZViewItem

Note: This is NOT the same seller or exact type I have, but looks identical to the one I have. My card reader also can read SDHC cards. YMMV.

EDIT: I just found link to another one that looks EXACTLY the same as the one I have. I edited the link above.