Personal Networks 
Facebook - mostly for friends and family
Twitter - where I am, what I'm doing, etc.
Digg - for sharing and tagging stuff across the 'Net
del.icio.us - organized sets of links are here
Hulu - sharing comments and favorited videos
Amazon.com - for book reviews and gift lists
YouTube - for sharing videos
Experimental or Inactive
Google Wave (beta) - just getting started with this one
MySpace - I prefer Facebook
FriendFeed - aggregates updates from a number of my social networks
Zune Social - I use a Zune but, so far, this social network doesn't do much for me
Orkut - now owned by Google but not very useful
Google - link to my profile info in the Googleverse
Knol - inactive so guess I don't have any knowledge units
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