No electronics (though I think there is a motor component that we haven't got) but DS7 loves Georello gears (interlocking cogs which can be wheels among other things, and various bits to let you build things with them). He was given a very simple set around age 2 which got a lot of mileage, and recently spent a long time's worth of pocket money to buy a more advanced set to go with it - there's a fair range. The big advantage is that at no stage has he needed adult help with it - the adults in our house have limited patience with lego!
