I learnt the risk of those signatures the hard way. I recently built a site, turning to a mate who claimed to have the handle on promoting I followed his advice and posted a few articles about my site in relevant forums to get the word out there to people in the field of health and fitness. Now while this added them links to my site it also opened up the ol' can of SPAM from people who have seen this tactic employed too many times. Hindsight being a great enemy, I should never have done that, is the negative publcity worth a link...hmmm in my opinion no, load of dedicated forum guys trashed my posts and my forum rep which just killed all of the power of the posts I have made since. My feeling is make a great sight, and write about what you really want to say in forums, if people like what they read from you then maybe they will follow your profile link to your site. More over posting in forums to add that sig link is tedious, while posting to share an actual opinion is never a drain.