from Anjali Sastry

I use backpack to quickly set up shared pages. If you pay the $5 monthly fee, you can upload documents. And add pictures and other things.

If you use the free version, you can still set up useful pages. Invite other users (you need their email addresses) and they can edit the pages too.
Here's one quick page I made in the fall: http://anjalisastry.backpackit.com/pub/744900. Please note this is the public version of my own page--my own version of it allows editing, of course. This public page is for viewing only. Team shared pages allow for editing, notes, etc.

Backpack pages have to do lists, but they can be a bit unwieldy to manipulate. It may be easier to collaborate via editing the text in the "body" section of the page. BTW, I also found the writeboards to be unwieldy, but your experience may differ.

One cool thing about backpack is that each of your pages gets an automatic email address. Just cc or bcc this page with your entire email stream at the start of a project, and you'll have a little archive going from which you can create more organized content later.

here's where you start: http://www.backpackit.com/ to learn more or to set up your own account.