Chris from PyroElectro wrote a series article of Building A Robot.He built this robotic car named "cat robot" and what he said his own robot.It's a nice project and tutorial,special for beginner and unexperience.
Three parts have had.In part one,Chris introduced how to assemble motors with off-the-shelf robotic chassis and work properly .To get a feeling for how DC motor work in general ,what to expect from the mobile robotics platform at the same time. Part two, build up firmware for a microcontroller that can tell a motor controller IC to move the motors at specific speeds and directions. In short,motor control.Part three, integrated a standard Infrared Proximity Sensor with our robot so that it can sense objects that are infront of it .Now the robotic car can feedback about the world that surrounds it.
You can follow him to build yourself robot and make some creative with your project.Hope useful for you. Update will go on.