InfiniteThinkingMachine It is a place for teachers and students to share ideas and dialogue about 21st Century Learning Tools.
YackPack Chat online and messages are stored in a private and secure place.
Swivel Share data sets with others and collaborate on projects and topics.
Works well with Google Spreadsheets.
Twitter Micro blogs where teachers can ask quick questions of other educators.
An account is required. Useful for professional development.
(the above taken from SchoolLibrary.org
What are YOUR coolest learning and collaboration tools on the Web?