K.A.
My boys love Hexbug Nanos and their other "bugs" http://www.hexbug.com/
They are 8 & 11. My 2 year old daughter loves them too. The Nanos you can get "habitats" which are all sorts of tracks and stuff for them to run on. My kids will build huge elaborate things on their playtable and let hordes of the Nano bugs go to town. It is hillarious to watch! The cats will sit there and watch them too. If we're not attentive they'll run off with them!