Plan 9
Plan 9 Foundation
About Plan 9
Plan 9 Download

Nokia Bell Labs - Plan 9 from Bell Labs in Cyberspace! copyright of Plan 9 transferred to Plan 9 Foundation which have made it available under an MIT license.

Plan 9 from Bell Labs, main page. (dead link)
Plan 9 from Bell Labs, introduction to Plan 9. (dead link)
Plan 9 — The Documents (Volume 2) (dead link)

cat-v - Plan9

Plan 9 from User Space (aka plan9port) is a port of many Plan 9 programs from their native Plan 9 environment to Unix-like operating systems.

The Bendyworks Blog - Getting Plan 9 running on the Raspberry Pi

mechiel lukkien's homepage see also mechiel lukkien's hg repo