Mega Rigs are a great throwback to the modular toys of the 80s. Think Jayce and the wheeled warriors or Starcom. They feature tons of parts and play action. You can disconnect and rearrange the parts to form a multitude of combinations. In the past they have done trucks, ocean tankers, submarines and such, this year the theme is space vehicles.
Unfortunately at Mattel's display they didn't show this functionality with any crazy combinations. I'll have some reviews up here in a little while. But trust me, these things are cool. Maybe not something you'd want to collect per se, but definitely fun to play with.