Senran Kagura Burst!

Oh, there's some rhythm game she loved. Rhythm Thief or something.

Animal Crossing! At least from my experience, it was the game that drew my sister's attention the most, so I gave her a 3DS for Christmas along with that game and now we play together all the time.

Rayman. It's a cute game and great for kids. It's a bit silly and I think kids like that kind of stuff. No pedobear.

Animal Crossing would be a change of pace for her as long as she knows how to read, the game itself is pretty straight forward and it's highly addicting.

I don't know.  I thought Rayman was frustratingly difficult without the multi-player.

But.. Cake Mania is the bomb..

The way she was obsessed with it, you might be right.  Just looked like some free PC flash game, to me.  

Animal Crossing is not only engaging and fun, but there's a lot of reading as well and can help develop that skill set for her, as well as social interaction and the value of collection and bargaining.

Other than that, Nintendogs if fun too, and if you don't mind mild violence, Star Fox and Pokemon are probably okay for 7-year-olds.

I'm kidding around. I honestly do know about Cake Mania though and it is indeed a flash game. It's one of those casual strategy games first released on PC (Like Diner Dash but instead of good it's pretty bad) and later spammed on other consoles.