Do posts here and on other forums count as multiple backlinks? This tool lists all the posts for a given site: http://www.backlinkwatch.com/ Do they all contribute or do search engines only give credit for one per domain?
At least multiple backlinks could increase your sites page rank. I also checked this theory several times in a couple of link networks. My conclusion is that sites having 10 backlinks on every 100 domain rank higher than sites having only one backlink from all those 100 domains.