PETROS  
   By Trumpet Software International, 32-bit microkernel OS for x86 PCs coded in Object Pascal variant. Built from first principles to focus on small size, modularity, and be fully compatible with Win32 and industry standards; reads FAT-12/16/32. Low cost; f
   http://www.petros-project.com/

BugOS  
   New microkernel operating system for x86 computers, many features: network and Internet modules, file system (FAT); kernel handles memory, tasks, micro kernels, and some base devices: keyboard, video, hdd, and ramdrive.
   http://bugos.nop.hu/

Microkernel-based and similar Operating Systems  
   Includes links and brief descriptions of microkernal based operating systems.
   http://www.cs.arizona.edu/people/bridges/os/microkernel.html

The Open Group: Advanced Research  
   Page listing several research projects: microkernel OSs (MK7, MK++, AD3) and other modules (CONVERSANT, CORDS, GIPC, SHAWS).
   http://www.osf.org/RI/

Microkernel-based OS Efforts  
   By Christopher Browne. Brief, clear descriptions and critiquing of microkernel design concepts, with some links. Puts much current activity in larger context.
   http://www.cbbrowne.com/info/microkernel.html

React  
   Effort to clone Windows NT OS; goals: to run without change Win32 programs (binary application compatibility), Windows NT drivers (binary driver compatibility); needs i486, 16 MB RAM, 40 MB free disk space. [Open Source, GPL]
   http://reactos.wox.org/