Jorum is starting to seem useful. This is a repository of online learning materials at tertiary level. Everything must be licensed openly and no login required to access materials.
Interesting tool I came across after following a discussion about people changing their CC licence and then end users struggling to prove that they had fairly used under an earlier license.
"mageStamper is a free tool for keeping dated, independently verified copies of license conditions associated with creative commons images. You can use it to safeguard your use of free images from license changes, or to prove you are the original image creator."