There are many websites that frequently update huge lists social bookmarking sites. You can simply search it through Google. The websites used to update those sites list with both Google page rank and Alexa traffic rank as well.
Thanks for sharing such helpful Social Bookmarking list!!
Social Bookmarking sites are good for both traffic and backlinks. Now the sites that nofollow may not help as much but if you can submit to social bookmarking sites that allow dofollow links, that will help.