Hi
Not sure if this is a repost but I would recommend checking out SocialAdr
They offer multiple types of accounts but the Free version can get you up to 400 monthly backlinks from social bookmark accounts.
Share others bookmarks, get credits = Others share your bookmarks
This is a great system and will certainly get you some nice visibility and improve your SE ranks
I am using the free account now but am considering upgrading as results are starting to show.
socialadr.com