The classic dungeon crawler Diablo is being ported to the Sega Dreamcast by @azi_hassan.
The port is being created using Devilution, and is currently in a somewhat rough state; there's no audio and the network functionality isn't present – plus there are "other unspeakable things" that Hassan has done to get it to this point. The game even crashes because the save file is so big.
However, despite all of these teething troubles, the port is looking pretty impressive, considering how early in development it is.
You can see it in action below.
The Dreamcast is getting plenty of port action at the moment; DOOM 64 was recently ported to the system, and GTA III is in development, too.