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.
KeyKOS Nanokernel Architecture - - Thorough architectural analysis of persistent, pure capability, for IBM S/370 mainframes, by Key Logic, Inc; text, diagrams, comparison, references, bibliography, contacts.
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.