Ok lets start a list of all the best forums which allow signature links. List what type of forum they are and the URL. I'll start: http://forums.digitalpoint.com We all know what it is about.
DP is a crap suggestion. You need god knows how many posts to start showing your sig and they have to be spread over a very long time. DP is not a good place for signature link building. And Google only counts one for real anyway so the whole idea is rather useless IMO. Maybe just for traffic but that's it.
Uhm, the best forums for links are always the biggest ones related to the topic of your website, as those will bring targeted visitors as well, so my answer is http://www.google.com (to find those forums).
Really I did not know that. So after finding a forum which allows signature links how do you know if its worth it or not? I thought DP was good but I was wrong.
Lots of forums have set up nofollow for robots anyway, so what minimal gain you may have gotten out of it in the past is pretty much 0 on alot of forums.
Posting in forums just for search engine related benefits is a total and complete waste of time. My 2 cents.
It depends - I guess you could sell all of them, even it if its not to build up your backlinks - it's good to help promote your website(s).
True, I have actually drummed up a lot of business using this method. It takes time, but I ofter receive emails: "Hi, I saw a post you made on xxx forum and am interested in your services".