As for my experience about forum used for linkbuilding yes it helps me bout facebook I thought its no follow ? but in one way I get some traffic from it and some friends linking my site
i think or as i know its yes forum posting help you in link building so just do continue but our chosen forums must have huge numbers of visitors if you wish to earn with ad sense
yes, fourm submission is the best way of link building,every site give me a link and user check for this link.