Originally Posted by AVC

Exactly, posting in forums for SEO is wasting time, 10,000 signature links pointing at your sites even if followed will certainly be discounted by the SE's.

Many of the link farm directories promoted on DP were banned from Google's search index because the link farmers purchased links from many of the signature spammers who post there for income from pimping out signature links, so there is the value of forum SEO (spamming and signature link abuse), these sort of con men ruin it for legitimate contributors and hurt the entire webmaster community.