Writing articles and submitting it to following popular sites with your URL link. Also publish the article in your site as a separate web page.

http://www.ideamarketers.com
http://www.marketing-seek.com/articles/submit.shtml

Write ezines and publish it in http://www.ezinearticles.com/add_url.html. Give the ezine free for download with a link to your site. Archive your ezines in your web site too. Related links will be more valuable than links from unrelated sites. Quality of the links will determine your ranking.