I'll fill in some more details later for this beta version of my robot. Briefly, the code is in NXC, I use Lego Mindstorms and the NXT Camera. To follow the line I use a simple PID. To get close to the ball I don't use one but I should (and will in Version 2!). The robot uses the sonar to find objects by the road. it uses the light sensor to detect whether it found the right object.
I intend to clean up my code and release it later this summer. If I don't, please bug me about it!