SlackeReviewS has been slackin' on the reviewin'!!
I just played an awesome custom mod of super mario bros. 1 on the website supermariobroscrossover.com and its fun as hell! You can play through all of the levels as one of your favorite 8-bit characters from your other 8-bit titles! You can choose Ryu(Ninja Gaiden), Link(Zelda), Bill Rizer(Contra), Samus(Metroid), Simon Belmont(Castlevania), Mega Man and of course Mario. Each special character has each of their abilities from their own respective games. Each making the gameplay style completely different. You can play it using your keyboard or if you have a usb gamepad you can play it with the classic controls. Here is a video
Play the game here: