I can't lie I was pretty excited to see the preview video for this new mini packbot by iRobot. I had seen some renderings more than a year ago and thought it would be a really cool little bot. So after seeing this the other day I searched out for small tracked rover platforms.
I had remembered seeing a tracked rover at SparkFun so I looked there first. Sure enough they have the Rover 5 robot platform. It is 4 wheel drive tracked rover with independent encodors on each wheel. The platform is made by Dagu and can bee found at many hobby robot retailers.
I checked out Pololu and RobotShop which were also selling the DFRobot RP5 which has two motors and costs less than the Dagu chassis.
Since the two products above are simply chassis with motors there are some more complete kits available. I found one in particular from RobotShop that was a pretty near complete robot called the DFRobotShop. It is a tracked robot with a chassis that is a lot like a Tamiya kit that has been very popular with beginning robot builders. On top of a chassis and motors it's body also includes an Arduino compatible microcontroller, a built in motor controller chip and a battery holder that powers everything. Also it has cool blue LEDs!
I'm not sure that any of these platforms can satisfy my desire to have my own personal attack robot that can survive being thrown through plate glass windows and fall down flights of stairs on purpose but they all look like fun starting points.
Also checkout Cellbots. They make software that lets your android phone be the brains of your robot over a bluetooth serial connection.