I went and did it again!

http://thoughtfix.blogspot.com/2006/...host-mode.html

Lots of pics, parts list, and explanation here. All parts available at your local Radio Shack for under $10.

This provides power to the USB client device (keyboard, flash drive, whatever) and provides voltage on the +5V rail needed to turn on the tablet's USB chip.

Edit: When I fixed this post, I also fixed the spelling of the word "injector" so old links may break.