See also:

• Computers: Programming: Languages: Language-OS Hybrids  (8)
• Computers: Software: Operating Systems: Capability  (4)
• Computers: Software: Operating Systems: Extensible  (5)
• Computers: Software: Operating Systems: Microkernel  (132)
• Computers: Software: Operating Systems: Open Source  (15)
• Computers: Software: Operating Systems: Research  (3)

• dr'ex - Exokernel written in C/asm for the x86 architecture. Released under GPL.
• dr'ex: SourceForge - Information, news, forum, CVS, downloads. [Open Source, GPL]
• Elysium - Main idea: enforce no abstractions, rather, have them as options, to all levels of system: hardware, kernel and file services, ways users interact with system; based on exo principles. Descriptions, news. [Open Source]
• Exokernel - Growing article, with links to many related topics. Wikipedia.
• Exokernel: An Operating System Architecture for Application-Level Resource Management - Traditional OSs limit application performance, flexibility, functionality by fixing interfaces and implementations of OS abstractions such as interprocess communication and virtual memory. Exokernel address this via application-level management of physical resources. [ResearchIndex]
• Miranda - Planned features: Exokernel architecture, object-oriented, POSIX compliant, intuitive GUI, and best technologies: journaled main filesystems, LibOS modular library. Development documentation. [Open Source, LGPL]
• Miranda: SourceForge - Downloads, announcements, and a forum. Programming languages: Assembly, C, and C++.
• miray Software - Makes µnOS: 72k microkernel on 8k nanokernel client/server architecture based on OOP framework, symmetric multithreading, multitasking, priority based scheduling, fully interruptible, separated address spaces, and full memory protection. Free download.
• MIT Exokernel OS - Puts applications in control, runs 10x or more faster. Exopc and XOK versions run on x86 PCs. ExOS library gives user-level extensible implementation of Unix OS, so most applications compile and run with no change. Download. [Open Source, MIT]
• Nanokernel - Growing article, with links to many related topics. Wikipedia.
• Unununium Operating Engine - Claimed as radical new approach to OSs: no-kernel, self-modifying cells (like objects); single address space, useful where memory and CPU power is low, and maybe for AI. Written in self-modifying, modular assembly language. [Open Source, BSD]