The Small Device C Compiler (SDCC), targeting 8-bit architectures
Implementations for the Revised Report language
C compiler and dev kit for the z80 with assembly language libraries.
Scripts, Makefiles, tools helping to build TinyCC on Windows and wine.
Oberon family of languages to C translator for ARM, x64 and x86 archit
Mariko's GCC for the x68000
EMX compiler hosted on Win32
A minimalistic but complete standard Forth compiler in C
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)
High-level, meta-language, trans-compiler with virutal machine
C/C++ Compiler for the ActionScript Virtual Machine (AVM2)