[AffiliateSeeking]

Signatures does help quite a bit, not only in the Serps but also for gaining direct traffic. Although there are better ways of improving your serps, forums does help a little. I definately also know that it gets your site indexed rather quick as I experienced this with another site of mine a while back where I only listed it in about 10 forum sigs and the homepage of the site was indexed within 48 hours.

Although signatures does help in ranking a site, it doesn't help as much as some other methods as there are normally so many links on a page in a forum that you don't get much credit for your links. Also, I think Google would only count the first 20 - 30 links or something around that way when it comes to ranking a site as if they counted them all, then anybody can easily get hundreds of creditable backlinks by purchasing sitewide links from other online sites, which can easily be done.