sorry this is out of the blue, but I have a idea about the arena. (some ones probably said this but I can't be bothered to read through all of the pages so I will say it anyway)

I think there should be a quite steep hill going up to the pit button or spinner button.
or you could have a 1 or 2cm gap in the arena to get to the pit button or spinner button or even a flamethrower button. :twisted:

you could have a shallow pond or puddle to stop the non water resistance robots and incorage amphibious robots.

you could have a button on the ceiling which drops large ball bearing balls onto the other robots this might encorrage flying or jumping robots if they are legal.

I also thing there should be more completly autonomous robots in the arena so you could let fully autonomous robots have a larger weight limit.

These ideas don't have to be used but I think they are good ideas.