Some of my Mice!
Although I have never built a mouse that was able to get to the centre of the maze, I have had several does at building some!
Generic Micromouse Board
This board is a generic micromouse board designed primarily to drive 2 stepper motors being driven by little H-Bridge modules. However, all of the I/O ports of the Atmel Mega8/328 chip are available with a male and a female connector, so the board can be adapted as required - even for non-micromouse work.
The board dimensions allow this to be used on full-size, or half-size mice.
Mini-Me is an attempt at a half-size maze solver. I found these tiny stepper motors on Ebay, and also some simple H-Bridge driver boards. The boards are only make the connections to the motors, no clever chopping or logic. The motors are still driven by interrupt routines on the main chip. I have still got to find out if the motors have enough power to move the mouse!