Furl.net is one of the several social bookmarking tools available on the Web. I have been using it for about a year now and find it very easy to use, useful and it is free. The features I like about it is that when you save a Web-based document or site to your furl archive, it saves a snap shot of the web-page. This is great for articles and news items that may go off-line later on and I still want to be able to access it.
Furl.net has some great plug-ins that place quick save and access buttons in your favourite browser. It also lets you know if any other furl users have archived the resources you have. If anyone has you can look at their archive. Yes, you can make your archive public and share it with colleagues or students. There are tools to help you embed your listings into other web-pages. I have managed to embed portions of my list into my Blackboard courses.
Furl.net also have a full suite of tagging and labelling tools for your items, including a tool for converting your referencing into common citation formats like APA and Chicago. Check it out at http://www.furl.net/
Feel free to browse my furl.net archive at http://www.furl.net/members/rodcorbett