Hobby operating system, bootloader, kernel, drivers, C library
Market leading real time kernel for 40+ microcontroller architectures
freeRTOS for Arduino Uno, Goldilocks 1284p & Mega 2560
Indipendent distro uses inary package system. Sulin is roolling donkey
Beamology: Semicom Project Management
Open-source RTOS and Embedded Systems Toolkit for C++ and C
Android, DOS, FirefoxOS, Linux, MacOS and Windows all in one..
A Development Framework for Coldfire
CMAKE build enviroment for LPC2000 and LPC17xx Cortex MCUs
A new OS
Nanux Kernel
SuperWikia: The Runtime/Realtime Environment for Codesmiths