Fiasco is a microkernel with real-time capabilities running on the x86 and ARM platforms. It is compatible with the L4 microkernel, which has set standards in microkernel performance and functionality. Fiasco is a fully-featured and secure L4 implementation with excellent real-time properties. It can run L4Linux, a port of the Linux kernel to the L4 interface which executes completely in user mode. The screenshot shows the DOpE real-time windowing environment running on top of Fiasco, with an instance of L4Linux running in one of the windows.
leJOS is a Java-based replacement firmware (OS) for LEGO Mindstorms programmable bricks, including RCX and NXT. It supports threads, exceptions, synchronization, floating point arithmetic, strings, and so on, but there is no garbage collection yet. It is also designed to be portable to other small devices.
GENDIST (the Linux Distribution Generator) allows you to easily create your own special distribution. It creates a makefile-based build system for your distribution, and helps you to automate the following three tasks: maintaining your root filesystem, maintaining your "CD filesystem" (in case you create a bootable CD), and packaging everything on media.
kernbench is a CPU throughput benchmark. It is designed to compare kernels on the same machine, or to compare hardware. It runs a kernel compile at various numbers of concurrent jobs: 1/2 number of CPUs, optimal (default is 4xnumber of CPUs), and maximal job count. Optionally it can also run single threaded. It then prints out a number of useful statistics for the average of each group of runs.