Etherpad

Etherpad was introduced to me yesterday. It is one of the new social collaborative tools which are commonly called Web 2.0
Etherpad allows up to 8 people to collaborate on the same document, at the same time.
As each user logs in to the 'pad', which has a unique URL, their contributions can be shown highlighted in a particular colour.
A document or collaborative resource such as a set of useful URLs can be created quickly and then saved and copied into other programs such as Word for further editing and formatting.

Could be useful in a number of situations...