swtchboard

Swtch.com has 3 URLs listed in 2 Dmoz categories.

Libtask
A coroutine library for C and Unix.
http://swtch.com/libtask/
Top/Computers/Programming/Languages/Concurrent

Plan 9 from User Space
A port of many Plan 9 programs from their native Plan 9 environment to Unix-like operating systems.
http://swtch.com/plan9port/
Top/Computers/Software/Operating_Systems/Network/Distributed/Plan_9

9vx
A port of the Plan 9 kernel to run as a user space program using the vx32 sandboxing library in *BSD, Linux, and OS X systems.
http://swtch.com/9vx/
Top/Computers/Software/Operating_Systems/Network/Distributed/Plan_9