From my experience, the only visitors that I seemed to attract from DP were hackers and content thieves.
I have to agree with dawg about the signature links. We have tested this extensively and the only value we saw with signature links is from forums that focused on a similar topic as the site being linked to. We saw no positive ranking effect whatsoever from links from unrelated forums. I am sure that opinions will vary on this topic.
The only value that most forum links may have is from the occasional traffic that they drive.
"It's inexcusable for scientists to torture animals; let them make their experiments on journalists and politicians." -Henrik Ibsen