Social Bookmarking Sites:

http://www.blinklist.com/

http://del.icio.us/

http://www.fark.com

http://blogmarks.net

http://smarking.com/

http://segnalo.com/

http://www.shadows.com/

http://www.gifttagging.com/

http://www.simpy.com/

http://www.wists.com/

http://www.feedmarker.com/

http://lilisto.com/

http://ma.gnolia.com/

http://www.faved.net

http://www.spurl.net/

http://www.blummy.com/

http://myweb2.search.yahoo.com/

http://buddymarks.com/

http://feedmelinks.com/portal

http://www.hyperlinkomatic.com/

http://www.linkagogo.com/

http://unalog.com/

http://tag.zurpy.com/

http://de.lirio.us/

http://www.furl.net/

http://www.linkroll.com/

http://blogmarks.net/

http://www.givealink.org/

http://www.looklater.com/

http://netvouz.com/

http://simpy.com/

Content Rating:

http://www.slashdot.org

http://doggdot.us/

http://www.listible.com/

http://www.digg.com/

http://www.blogmemes.net/

http://www.blinkbits.com/

http://www.netscape.com/

http://www.spicypage.com/

http://www.shoutwire.com/

http://www.youhypeit.com/

http://reddit.com/

http://www.rojo.com/

Social Networking Sites:

http://consumating.com/

http://www.blogcatalog.com

http://www.linkedin.com/

http://www.ning.com/

http://www.facebook.com/

http://www.myspace.com

http://allconsuming.net

http://www.othersonline.com/

http://www.mybloglog.com

http://www.tickme.com/

http://www.orkut.com/

http://standpoint.com/

http://www.meetup.com/

http://www.43things.com/

http://www.43people.com

http://www.43places.com/

http://www.efamilyties.com/

http://www.9rules.com/

Video Networking Sites:

http://youtube.com/

http://www.broadcaster.com/

http://www.dailymotion.com/us

http://www.metacafe.com/

http://vsocial.com

http://www.springdoo.com/

Micellaneous Social Sites:

http://alexadex.com/ad/

http://www.jot.com/

http://www.spinspy.com/

http://googlemark.org/

http://www.meebo.com/

http://www.slawsome.com

http://www.stumbleupon.com/

http://rollyo.com/

http://quimble.com/

http://www.twitter.com/

http://metawishlist.com/

http://www.seomoz.org/ugc

http://www.rawsugar.com/

http://www.squidoo.com/

http://wink.com/

http://kinja.com/

http://tailrank.com/

Wiki Sites:

http://swicki.eurekster.com/

http://www.wetpaint.com/

http://pbwiki.com/

Job Sites:

http://www.jobsinsearch.com/

http://cssbeauty.com/

http://www.pagebites.com/

Organization Sites:

http://hipcal.com/

http://www.backflip.com/

http://www.connotea.org/

Tagging Sites:

http://www.citeulike.org/

http://www.tagtooga.com/

http://tagalag.com/

Photo Sites:

http://flickr.com/

http://www.slide.com/

Music Sites:

http://odeo.com/

http://www.mystrands.com/

http://www.last.fm/

http://upto11.net/

Political Sites:

http://gabbr.com/

http://www.newsvine.com/

http://www.blogniscient.com/

Shopping Sites:

http://www.judysbook.com/

Program Sites:

http://www.campfirenow.com/

http://www.basecamphq.com/

Feeds Sites:

http://www.feedburner.com/

http://www.tagsy.com/

http://www.feedmeme.com/

http://technorati.com/

Maps Sites:

http://www.wayfaring.com/

http://www.frappr.com/

If you know any social media site other than this list, please post it here in your comment.