Now here's an old one - I did this back in 2002 or early 2003, as both an experiment and a break from my classwork. I loved the idea behind the open source fighting game engines that folks used to combine all their favorite fighters... but I wanted to take it up a few notches. I wanted to do one in HD.
Rather than designing and animating an original character, I decided to HD-ify Felicia from Capcom's Darkstalkers. This meant scaling up her sprites, printing them out on animation paper, and scribbling in a more detailed version on the back... My original plan was to do this with all of her sprites, but I'm surprised I made it this far. It's a lot of work for no real payoff.
I like to think that if I were to make another attempt now, I'd do a much better job... But I'd much rather use an original character, or at least do something that isn't a glorified trace-job.
Oh My GOD! This is made of pure win!!!! Maybe you should go back to it, considering that Darkstakers might be coming back. Ohhhh, wouldn't it be cool if they made an HD version...or perhaps used the same engine they used with Street Fighter four with all the artsy-ness?