Informative thread but back links are the most important factor when it comes to the search engines deciding where to rank your website.
Building SEO links is the process of creating incoming links to own website. This can be done by reciprocal links, being listed in e-zines, directories, search engines, etc. You can build links using such following ways:-
Comments on blogs.
Web 2.0 links.
Profile linking etc..
I agree with webhosting1. There are many ways to build your SEO, social bookmarking is one.. I would also add publishing press releases and adding video posts if possible.