SEOMoz has a great blog post on Spamming the Square - creating content that seem legitimate, but underneath are really just a way to build links. Another example: - Adding a story to Digg Any other examples out there?
Sure. I post on forums (not here ) as an 'expert' in certain areas. When suitable, I drop a link to my site. Other times, I disagree sharply with the experts on forums. The traffic I get from one specific forum to one of my financial sites is measurable and far more than I get from all my directories and other links combined. Create controversial articles and label it as 'pros and cons to subject X' or 'subject X information'. Works well when most of the industry is all headed one way and you've got a counterpoint that you can back up. I got one site dmoz listed just by doing that. The entire industry selling a specific service was all gung-ho on it; I detailed the flaws in their arguments and pointed out cons to the service. Never really marketed the site yet it does well in the serps.
A successful marketer is one who can pretty much spam, spam and spam without EVER making others think you're doing anything except providing them the BEST content or services.. I personally get good traffic from my wikipedia profile...I have however never left my links on any wikipedia article pages. If i do include links in wikipedia it is to authority sites in my niche that aren't my direct competitions and just provide good information without any adsense or anything. Seems to be working..