this was interesting as well, id say relevant in context
5) Forum Posting/Signatures
What is it? You post on relevant forums and include links in your posts to your site. You also take advantage of the signature feature so that every one of your posts has an optimised anchor text link to your site.
Hat Colour: Light Grey
Pros: Forums don't have nofollow in their user generated content very often. If you start a thread yourself, you can control the title and much of the content of the page your link will sit on, thus ensuring relevancy in the eyes of the search engine.
Cons: Forums have a lot of outgoing links so the link value per link is devalued greatly. Therefore, not a lot of 'link juice' will be passed via links from forums. Many experts in the industry are of the opinion that forum signatures are of very little SEO value but that they're very useful for getting referral traffic, especially if from a respected poster.
Should you do it? Yes, but don't centre your campaign on this method. Make sure you don't spam the forum (by not participating in it and then immediately plugging your business blatantly) and be sure that its niche is relevant to yours.