The Small Device C Compiler (SDCC), targeting 8-bit architectures
SUNY Stony Brook Pascal for the IBM/360 written in XPL
C compiler and dev kit for the z80 with assembly language libraries.
Implementations for the Revised Report language
Ada cross compiler and libraries for AVR µCs
A "Just Enough Language" compiler targeting the 6502/Z80/6809
Micro Programming Language - A Portable Language for Micro Computers
Homebrew toolchains for wii, gamecube, 3ds, ds, gba, gp32 and psp
A C Compiler/Editor for Retro 6809 Machines (Colour Computer/Dragon)
Moved to https://github.com/davidgiven/ack
C/C++ Compiler for the ActionScript Virtual Machine (AVM2)