Thoughtboxes - organize everything you do

"Thoughtboxes is a free site that allows you to get organized using boxes that act like sticky notes. You can create categories and then create "thoughtboxes" in each category. You can use the boxes for to-do lists, notes, lists, links, and more."

http://educationaltechnologyguy.blogspot.com/2011/03/thoughtboxes-organize-everything-you-do.html

http://thoughtbox.es/

Zotero

"Zotero [zoh-TAIR-oh] is a free, easy-to-use tool to help you collect, organize, cite, and share your research sources. It lives right where you do your work—in the web browser itself."

http://www.zotero.org/