I'm still working on the WIKI but the robot is finished, Check this out!
You are free to leave a comment in the Forum/General Discussion.
Awesome what kind of sensors did u use.
Thanks.
As for the sensors I used...
Sparkfun IMU Combo Board - 2 Degrees of Freedom - ADXL203/ADXRS300
Nubotics Optical Encoder
http://www.nubotics.com/products/ww02/index.html
That's it!
This is exactly what I am trying to build. I have started with servos and a Ping))) sensor to measure the distance to the ground, but that is very sensitive to ground being level. I have a dual axis accelerometer and a single axis gyro from sparkfun so I intend to use these for balancing. I am building right now the encoders for the new DC motors I got (100 RPM @ 6V). The only thing I don't quite understand how to implement the Kalman filter. I haven't seen any project like this to have the code available. Perhaps that's why there are only a hanfull of them. If you think you can give me some advice or even better a chance to look at your code, I would be eternaly gratefull.
Here is the tutorial I wrote on the simple balancing robot I have built, based on some code from Parallax forum:
http://www.societyofrobots.com/member_tutorials/node/185
It has the code in Bascom and Arduino.
heheh - not horribly on topic, but that looked like me when I have had too much caffiene! /twitch! 
on a more serious note - have you started working on movement/roaming code?
Hi,
I've been there:
http://boram.wikidot.com/system-modeling
and I'd like to say a nice explanation and cool design...do you share your own Kalman filter code and/or other files of your project online? I couldn't find on the boram. I'm just developing a version of IPRobot and it's helpful to see more example (I've gathered a couple of them already).
If possible please let me know where to get your code 