I've been on a huge NES kick for a while now, and I'm working on building up my collection again. While working on another project to convert NES controllers to USB inputs I found RetroZone. Apparently they offer homebrew NES games on NES carts that play on a real NES.

One of them is Battle Kid: Fortress of Peril, and I think I may have to pick up a copy of it. Check out the video, and hopefully the cart gets back in stock soon.