Hi,
I went to the bigbang fair (in Birmingham) which I would definitely recommend going to next year as the kids got a load out of it!
Anyway, while I was there I bumped into Robotiky - they have a really cool little robot that teaches programming.
In fact they have an online demo of their software that works without the robot as it is just a website - really worth checking out www.robotiky.com/demo
It goes through programming really simply - even I could understand it, and the kids pick it up scarily quickly!
(I couldn't for the life of me remember how to spell their name or web address for ages hence they delay in posting this! hint hint, if you guys at Robotiky are reading this pick an easier to spell name 
)