dont know much about myspace but its good for marketing point of view depends

Yes, I too participate in forums. It does help in increasing the PR. if u go for the relevent forums it will be very useful.

I'm still not seeing links that i know exist... If i use the link: command in google... why is this?
thanks

Google only updates the link count every X times a year, and even then, it's not entirely accurate. All part of Google not wanting you to see exactly what is under the hood of their ranking algorithm.

However, definitely go to www.google.com/webmasters and use theri Webmaster Tools to the fullest - they give lots more details and more accurate statistics there regarding sites that link to you.

It obviously makes some difference as after i started putting my email in my sig ive got a tenfold increase in spam

That's right if the forums allow external links. If the pages where your link gets placement hold content similar to your industry, the links should always help not only in search engine rankings but also establishing your brand. Forums or blogs are the places where people can find useful information now since they hold different views of different people.

Yes, this has generated a lot of traffic for my site and it has resulted in increased exposure on the search engines.

I think posting in forums definitly brings traffic to your site. especially if you are able to help someone out by answering a question or posting a helpful article.

I have had many people contact me through forum posting with various inqueries about the different sites that I work on.

Forums postings seem to get the word out on a our websites and brings quality traffic to them.

As far as backlinks go, I dont know how true that always is. This forum provides backlinks but many dont.

Also I think if you post in a forum for the purpose of backlinks, may end up getting you banned, so be helpful and follow the rules in any forum you join.

I wouldn't advise anybody to put their email in their signature file. Definitely add your url(s) to your signature file. Don't forget that your contributions (and accompanying sig files) stay on a forum for as long as the forum exists and so are a constant potential source for traffic.

As for MySpace, I agree with Csgal's doubts as to its efficacy as a source for quality leads unless, of course, you have a site that can serve a largely youth-entertainment market, if you know what I mean.

I believe in forum posting. I also get more quality visits from them than I do from Google.