Free RTOS
Freertos is a portable, open source, mini real time kernel. a free rtos for small embedded real time systems
http://www.freertos.org/
LynxOS
Rtos (real-time operating system) and embedded linux os for embedded and rtos-based systems.
http://www.lynx.com/
Embedded Windows
Embedded Windows
http://www.microsoft.com/windows/embedded/
Embedded Java
This page contains embedded at a glance related to java se.
http://java.sun.com/products/embeddedjava/
CKernel
The c kernel pages and c programming guidelines
http://www.ckernel.nl/
Opensource voor handhelds
Opensource voor handhelds
http://www.handhelds.org/
Parallel & Distr. OS
Parallel & Distr. OS
http://pdos.csail.mit.edu/
SMX RTOS
Smx no royalty rtos for arm, coldfire, powerpc, and x86 embedded systems. real time multitasking kernel, usb h/d/o, fat flash filesystem, tcp/ip, gui. designed for demanding real-time apps.
http://www.smxinfo.com/
RTems
RTems
http://www.rtems.com/
Real-Time JAVA
Book - the real-time specification for java
http://java.sun.com/docs/books/realtime/
QNX
QNX
http://www.qnx.com/
VxWorks (WindRiver)
VxWorks (WindRiver)
http://www.wrs.com/