One day I was surfing Emutalk and I saw how easy could be starting a new emulator project.
The point was emulating an old Chip-8 interpreter, but I wanted to go a little further trying to run it on mobile phones, so I coded it using J2ME.
It runs pretty well and its compatibility is near perfect. I bundled it with some free games I found on the net.
You can grab the source code from GitHub.