Here's a couple links that may help.
http://www.solarbotics.com/
http://www.pololu.com/products/gearbox.html
The scratch built crawler I built is geared very low. I don't know the exact ratio off hand but it's slow.
BTW...How have you been Killer? I've been out of the loop for quite sometime and have been doing the Micro Flight thing lately.
My 1/24th crawler got borrowed for an apearrance at a 1:1 4x4 club meeting not long ago. Here's a pic.