This one
http://www.epos-ps.com/products.asp?pid=1275&ppid=1278
would be nice. It claims to be Windows-only, but the spec sheet says that any HWR software can translate the notes to text, so they're most likely in standard digital ink format.

If only the usb port of the N800 were host-enabled...
If only there were a Linux program for converting digital ink to text (Journal has a -- very! -- embryonic form of it)...

Of course, if we had digital ink conversion on the N800, we could use Xournal to take notes and buy beer with the money for the digital pen.