Lord of the Rings, Return of the King -- co-op hack and slash at its finest. It's a gamecube game to play on your Wii. Level up with a just a smidgen of RPG.
Baldur's gate - ps2 or ps3 backward compatible - isometric dungeoun crawler
Marvel ultimate alliance 1 and 2 if you like the super hero thing.
PS3 Untold Legends Dark Kingdom
Xbox 360 / PS3 Conan
There are so many good ones. I loves me some hack n slash.