I love this mans channel
Death metal covers of Katy Perry, Justin Bieber, Mary Poppins, Grease
Bluegrass version of Dr. Dre
Reggae version of Nirvana
Jazzy version of Dio

this one is one of my personal favorites



here's his channel

https://www.youtube.com/user/AndyRehfeldt/videos

this is another great one




who am I kidding? they're all great