BigBoy the author of DreamSpec recently told me of his plans to have a go at creating a Commodore64 Emulator for Dreamcast,and guess what? ,yes he now has one running this is what he says:

DreamCast C64 emu now running!
Pyjamarama isnow running (around 1/2 speed) on an actual dreamcast….
I think I need a faster 6502 core though…. its using mine just now, and it looks a bit slow. Although the PEEK and POKE on a c64 are hell!!!

It is called DC64,though his site has no information on it,he posted it in our forums here ,this for me is one of the very best computers that could have been emulated on the Dreamcast,the homebrew scene for the Commodore64 was massive,so i wish BigBoy all the best with this new project