FreeBSD - My next favorite FOSS system after Linux.

FreeBSD Handbook - Unlike in the Linux world, "manual" is not a dirty word in FreeBSD.

FreeBSD Diary - Fun little news / resource / community site.

BSD Guides - Guides to all the *BSDs, Free, Open, Net, etc.

BSD For Linux Users - Fantastic ambassador between the cultures of BSD and Linux.

Minix - The operating system for people who disagree with Linus Torvalds.

Plan 9 From Bell Labs - It exists just to spite us all.

Nine Times - News about Plan 9 and other phenomena.

Inferno - The spiritual successor to Plan 9.

The HURD - The GNU Hurd system. It's not a myth!

Open Solaris - As long as it's still kickin'.

Nexenta - An Open Solaris blended with GNU/ Linux.

Haiku - The FOSS successor to BeOS.

AROS - The FOSS successor to Amiga.

The OS Developer's Wiki - The exciting fringe of possibility.

Many Systems on a Powerbook - Mad genius coaxes a Powerbook 17 to run dozens of alternative systems, for no apparent reason. Long live geekdom!

Reviews of 10 alternative open source OSs. - Little thumbnail sketch reviews.

Wikipedia's OS comparison. - Both proprietary and FOSS, compared side-by-side.

My own Gimp Linklist - A post on my own blog linking to Gimp resources.

Gimp for Photos - Italian site with struggling English, but clear tutorials.

FSM Free Software Magazine - One of the strongest FOSS resources.