Creating Tools To Build Links
Creating free tools is perhaps the most powerful link building technique in the known universe. One example would be creating myspace layouts. People use those freaking layouts like crazy, and you can embed a link in each one. People will click on the links to find your site, and then they will want to use the layout as well.
When a tool you made goes viral, it can result in a massive amount of links for your site. Other examples of tools that can be used to get links are WordPress themes, gadgets, and widgets that people can use on their sites and blogs.