For the Commodore 64 there is Lunix
http://lng.sourceforge.net/
There were a buttload of Lunix distros for the Amiga, 68k and PPC but I never followed it. Minix was an early one.
Neither Lunix nor Minix is Linux, and there really was just one distro ever that supported m68k and that was Debian. In addition there was a redhat based package repository maintained by Jes Sørensen, who also was chief m68k kernel dev for many years. Today Debian wants to get rid of old archs that delays releases, it was just barely along with Debian Etch, and there is no Debian Lenny for m68k. The kernel devs are considering alternatives.