"Vidque is a new service that aims to help users curate their own collections of the best videos available on the Internet. Vidque allows users to grab videos from YouTube, Blip.tv, TED, and Vimeo to put into their own collections that they can share with others. You could also think of it the way TechCrunch did in describing Vidque as video bookmarking."
A superb, 'must try' collaborative whiteboard site. Invite collaborators to draw, write, screen capture and upload documents onto your whiteboard in real time. Great for webinars, distance learning, howework or group work in class.
"This site aims to inspire teachers to increase the communication and collaboration in their classrooms using web based tools such as blogs, wikis and social bookmarking tools. The examples given on this site focus on using these web tools in Design and Communication Graphics classrooms but many of the activities outlined can be easily modified to be used in different subjects and to cater for many different ability levels. The site explains what the web based tools are, what they can contribute to teaching and learning, how they can be integrated into the classroom using simple and clear examples, and how to enable pupils to use them saf"
I tried this a few years ago Nd decided to stick with diigo, but it is still worth looking at and really depends on what it tpis you are trying to do...