Idea, probably a dumb one but an idea.
take a dreamcast shell. Gut the the thing. Put in a dvd drive that will work with a lid design.
Now those new ram slot raspies open up a few possibilities if you can get a support board made to do this. Four usb connectors up front to line up with the controller ports, you'd have to mod the modem thing so it could house eathernet. Stick wifi in there too because why not. And in the serial cable in the back like the real hardware has and vga out since any decent tv now has vga.
Pity there's likely no chance a raspi can emulate dreamcast. I suppose if you could program for two of them to share the load it could. But the point is more livingroom friendly design with a dvd drive and front facing usb. Now if you put an IR sensor up front for a remote that would be awesome but whatever. It'd cost a fuckton if not in money then in design time and work.
And have. It boot up into xbmc and have that serve as your launchpad for dvd, youtube/screw attack/whatever as well as your emulators.
But if you could get it to play actual dreamcast games at regular speed that would be nifty.
Bonus points for having the dreamcast bootup logo thing