How many social sites is tooo many?

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A1 Webmarks
Backflip
Bibsonomy
Blinklist
Blogmarks
Bookmark Tracker
Buddy Marks
Connectedy
Current UPDATE: Went from social to TV to giving way to http://www.aljazeera.com/america.
Care2
Connotea UPDATE discontinued service on March 12, 2013 the creator http://www.nature.com/ is still running
del.icio.us
Digg
Diigo
Danogo.com   Has a placeholder but down
Facebook
Faves(Bluedot)
Fark
FeedMeLinks founder onto a new interesting product https://respond.ly/
Fetch is now http://www.connotate.com/
Fresqui
FriendFeed
Furl became Diigo
Funp
Folkd
Google Bookmarks
Hugg
Health Ranker now Health Bubble
Indianpad
Jumptags public part disable still can use as private
Ka-Boom-It
Kirtsy
Link-a-Gogo
Links Marker
MySpace
Mixx became popurls
ma.gnolia  
Meneame
myAOL  just good ole AOL now
Multiply
Mister Wong
MyLinkVault
myVmarks
Newsvine
N4G
Netvouz
Oknotizie.alice.it
OYAX
Plugim.com
Propeller
Rawsugar
Reddit
Seganlo
Simpy
Slashdot
Sphinn is now http://marketingland.com/
Spurl
StumbleUpon
swik
Symbaloo
Tagza
Technorati       
Twitter
Windows Live
wirefan.com
Xanga currently revamping themselves
Ximmy
Yahoo Bookmarks
Yahoo! My Web
Yigg

Yes, that's right there is 73 and I know this isn't all of them!

UPDATE: there are now several pages of social networks sites http://en.wikipedia.org/w/index.php?title=Category:Social_networking_services&pageuntil=Exxset%0AExxset#mw-pages