I am sharing a list of social bookmarking site that are trusted for backlink. Because from my experience, I have understood that though there might be a large amount of social bookmarking site you need to trust only those that are good in Google eyes.
I found a list. So here you go:
PHP Code:
Dofollow Social Bookmarking Sites:
Folkd- http://www.folkd.com/
Topsy - http://topsy.com/
Bookmark4you - http://www.bookmark4you.com/
Kwoff - http://www.kwoff.com/
Scoop It - http://www.scoop.it/
Tagza - http://www.tagza.com/
Karmalynx - http://www.karmalynx.com/
Social-Bookmarking.net - http://www.social-bookmarking.net/
Flixya - http://www.flixya.com/
One View - http://www.oneview.com/
StartAid - http://www.startaid.net/
Diigo - http://www.diigo.com/
SiteJot - http://www.sitejot.com/
Linkagogo - http://linkagogo.com/
BuddyMarks - http://buddymarks.com/
Blogmarks.net - http://www.blogmarks.net/
Mister Wong - http://www.mister-wong.com/
Rudan Bookmarks - http://www.rudan.biz/
Simpy - http://www.simpy.com/
Chicken Monkey Pie - http://www.chickenmonkeypie.com/
A1 Webmarks - http://www.a1-webmarks.com/
Monster Bookmarks - http://www.m0nster.info/
Delicious - http://del.icio.us/
Bookmark4You - http://www.bookmark4you.com/
MyLinkVault - http://mylinkvault.com/
Oyax - http://www.oyax.com/
Gozoof - http://www.gozoof.com/
Netvous - http://www.netvouz.com/
Bukmark - http://www.bukmark.net/
Xelo Bookmarks - http://www.xelo.us/
Kabayani Bookmarks - http://www.kabayani.com/
BlinkList - http://www.blinklist.com/
Tamilers - http://tamilers.com/
Buzz Bookmarks - http://buzzbookmarks.info/
Bookmarkall - http://www.bookmarkall.com/
Social Article - http://www.socialarticle.com/
H-Stream Links - http://www.h-stream.com/
XMarks - http://www.xmarks.com/
Ziki - http://www.ziki.com.au/
Dizzed - http://www.dizzed.com/
Feedmarker - http://www.feedmarker.com/
Khojlive - http://khojlive.com/
Friendfeed - http://www.friendfeed.com/
Connotea - http://connotea.org/
Blinklist - http://www.blinklist.com/
Newsvine - http://www.newsvine.com/