Let's see, there's the Subspace Emissary from SSBB, The Legendary Starfy, New Super Mario Bros. Wii, Castle Crushers (if that counts as a 2D platformer), Kirby's Epic Yarn, and Donkey Kong Country Returns.

I'm hoping to add Kirby's Return to Dream Land and Rayman Origins on that list after Christmas.

2D Sidescrolling platformers are my favourite game genre. Lots of action yet simple to learn and get into.