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
An open source ecosystem for IoT development
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
Embed C++ in Python source code, dynamically compile and access data
C/C++ Compiler for the ActionScript Virtual Machine (AVM2)
*** Moved to http://github.com/esumii/min-caml ***
Ada compiler support for TI MSP430 processors
Mini Python Compiler written in Java