C-64 standalone on batteries
I recently bought one of those Namco 5-games-in-one sets. Becky really likes Ms. Pac-Man so I got her that one. Along the same lines, apparently there is now a self-contained C-64 gaming machine. It runs on batteries and instead of just 5 games, you get 30 games pulled right from my Commodore youth. The linked article above also tells how to hack it a bit to see some extra things. After reading about, I think I will definitely be poking around for one on eBay.