Just started using Diigo for a place to store bookmarks for various projects I am working on. Very useful as I can now access the bookmarks from anywhere. The more I use it, the more I like it. Just started tagging my favourites into my various areas of research too, which I will share with groups when needed.
Introduced it to the students to gather some research, the highlighting tool is very useful. Also, as students can't save favourites in school this is a good work around.