Identi.ca is similar in concept to Twitter – 140 character-long messages, micro-blogging, etc. But … it’s an open-source service using free software. If you’re on Twitter you can get people’s ‘notices’ from Identi.ca – messages are pulled from one service to another. One good feature that twitter doesn’t have (yet): personal tag clouds. Also, big Tim (Berners-Lee) uses it so that’s a good thumbs-up where I come from.
‘Ward’ (Howard G.) Cunningham is the guy who came up with the first wiki ,which was launched in 1995. Wikis are software that allow people to create and edit webpage content – ‘open source/crowd editing’ if you like. The name comes from the Hawaiian for ‘fast’ because Ward’s idea was that pages could be edited quickly. Everybody has heard of Wikipedia, probably the most successful/famous/etc example of the use of wikis allowing anybody to contribute and edit articles involving a startlingly ‘organic’ and democratic degree of self-regulation.