I recently subscribed to the feed of my friends’ updates on Facebook. It’s useful, but Friend Feed sounds like it has potential to be even more useful: A way to aggregate and monitor all your friends (sources) online activities.

"FriendFeed and Plaxo Pulse let you designate friends, then easily add
feeds of your activities from other sites. The result is that each user
sees a continuous stream of updates from friends — Twitter messages,
uploaded YouTube videos, blog posts, shared Google Reader items, and
much more. Both FriendFeed and Plaxo include community discussion
features, such as commenting on others’ items."

Crowdvine: A way to do pre-networking before a conference.