If you're looking for more Wii game recommendations:

Wii Fit
Wii Sports Resort
Mario Party 8

All dearly loved by my 6yo, and active enough that I don't really consider them "video games" in the usual sense.

He works up a sweat playing the kendo game in Wii Sports Resort.

Sports Resort requires a new wiimote attachment, and typically it is packaged with one. I bought an extra one so we would have 2 for the kendo game.

I haven't seen the new balance board. The only thing I'm aware of is the Wii Fit Plus (or whatever it's called) that adds more features and games. You can buy that as a simple $20 CD though.

Another game that is fun (if a bit cracked) is Wario Ware: Smooth Moves. It's basically short attention span theater, with a few hundred microgames: weird stuff like "pluck the nose hair" and "make an omelet", and very funny and entertaining.

It's not as active as the other games, however.

Similar, but the games are truly microgames as compared to Rayman.