SoftVMS is a Dreamcast Visual Memory System emulator for the Macintosh. It's been said before, but I'll repeat it here - this is NOT a full Sega Dreamcast emulator.
A screenshot is available on the WWW.
SoftVMS was originally developed for Unix by Marcus Comstedt. The Macintosh version includes the full source code in the archive, and I encourage you to submit improvements back to me.