If I were the devil, I would hang out by people's beds when they woke up and offer them more sleep in exchange for their souls. I know that when my alarm goes off, I would do some pretty stupid things for five more minutes of shuteye.
Of course, If I were the devil, I would also have Arrow sent to hell so he could perform "Hot Hot Hot" for all my devilish dance parties.
Oh, and I'd have pointy ears and a killer goatee. And I'd be red. And have a tail. Man, being the devil would be awesome.