Built a quick and dirty PIC16F88 based robot for classroom use. More info at
Men with Soldering Irons

3V0 I'm looking to sell my Mongoose kit to Colleges and Universities. Do you think your College would be interested (I noticed you're using Tamiya parts in yours)
It's got a SN754110 & 18F2525 (nice chip with a free C18 or Swordfish demo compiler)
You could use the 16F886 instead as it's pin compatable.

PS noticed you're interested in the ENC28J60, keep your eye out for the future kit Ladybug.

Bill,
I did a bit collage teaching prior to retiring. Currently I teach a few kids (4 total) at the local high school. Building robots is used to get them interested in electronics and comp sci.

Mongoose looks like a great robot. I opted not to use it because I want students to make as much of their stuff as possible. I choose to build a H-Bridge from transistors because building and repairing it will provide needed experience using transistors.

When we get to the place where we need feedback I will be taking a careful look at you rotation sensors.

BeeBop,
The greenhouse is scheduled for a major update. Wife wants to increase the length to 2x and add natural gas heat as a backup to the electric. Have not worked on the controls in some time but need to do so prior to frost.