Nathan's list

Here's the big list:
http://www.permacultureactivist.net/maillists/emaillists.htm

But I recommend:

http://lists.ibiblio.org/mailman/listinfo/permaculture
http://jasper.cmsarchitects.com/mailman/listinfo/pil-pc-oceania
http://groups.yahoo.com/group/pfaf
http://tech.groups.yahoo.com/group/midwestpermaculture/
and although this isn't technically permaculture, I find this
one really helpful:
http://lists.ibiblio.org/mailman/listinfo/nafex

It's the North American Fruit Explorers, which I might be into
more than most, because I'm planning on doing a lot of tree
crops.  The first two listed listservs are probably the best.

Rob's Notes

Books

Ecotopia - Earnest Callenbach

Edible Forest Gardens – David Jake

Humanure Handbook

Tree Crops J.Russel Smith

Groups/Lists

commonground collective

Dayempur Farm

Humble Pile “Salvation Jane”

Midwest permaculture group

permaculture list server

Soil Food Web/Farm

Web soil survey

wwoof (Worldwide Opportunities on Organic Farms)

Videos

Greening the Desert -Geoff Lawton

Various You Tube Vids -Bill Mollison

Cold Frames

Studies

Grape Jelly Experiment

Green supply stores

Greenmaker