From the Wikimedia:
"Participatory Media include (but are not limited to) blogs, wikis, RSS, tagging and social bookmarking, music-photo-video sharing, mashups, podcasts, participatory video projects and videoblogs. These distinctly different media share three common, interrelated characteristics:
- Many-to-many media now make it possible for every person connected to the network to broadcast and receive text, images, audio, video, software, data, discussions, transactions, computations, tags, or links to and from every other person. The asymmetry between broadcaster and audience that was dictated by the structure of pre-digital technologies dictated has changed radically. This is a technical-structural characteristic.
- Participatory media are social media whose value and power derives from the active participation of many people. This is a psychological and social characteristic. One example is StumbleUpon.
- Social networks amplified by information and communication networks enable broader, faster, and lower cost coordination of activities. This is an economic and political characteristic.
Etymology: The phrase Participatory Media was first used publicly by Greg Ruggiero and later popularized by blog researcher Rebecca Blood and others, such as Furukawa. In April 2006, journalist and media researcher Jim McClellan used the phrase Personal Participatory Media, which may distinguish between objective social media (scientific, corporate, pure information) and subjective/personal social media (value-laden, opinion, religious)." (http://en.wikipedia.org/wiki/Participatory_Media)
Overview of Participatory Media developments: a table giving access to autonomous media.
The Open Media Directory gives access to independent media as well.