Slideshare users can also manage collections of presentations, documents, videos, etc. and watch the activity and comments for each file, in addition to other common social business features such as tagging content, following other users, sharing by email, and tracking how many people like or reshare the document.

FORBES: What Do I Do With this Customer Lead From My Social Network?

Facebook last month launched a new Groups feature, allowing users to create groups on the social network and add friends by tagging them in the group.

FORBES: Zuckerberg: Facebook Groups Is One Of Our Fastest Growing Products

His vision for Clutch is that it will combine three functions the tagging of Pinterest, the social element of Facebook, and the online shopping of Amazon (AMZN).

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The top five in 2010 are Social networking, Wikis, Peer to peer sharing, Video sharing and then a three way tie between tagging, RSS feeds and Microblogging.

FORBES: Business and Web 2.0 An interactive feature