While backlinks are the most important factor in SEO (Search Engine Optimization), particularly when they are naturally occurring, highly relevant and driven by great content, outbound links have their place in SEO as well.

Outbound links serve the publisher so that the reader more fully understands the sources of information used by the publisher (writer).  These links serve to increase and maintain credibility of the writer.  They also serve to add backbone to the information and / or the message of the content being offered by the writer.

Letting people know what information you are relying on to become the expert you are in your field lends credibility and foundation to your writings.  Giving credit where credit is due is just a good human characteristic you should have towards building credibility, loyalty and a following.

Authorities rely on other authorities to build a case or make a point.  Moreover, “ye who gives shall also receive” … so by giving to credit to authority sites you increase your opportunity to be linked to by an authority site.  This is kind of the SEO version of the golden rule applied specifically to linking.

So, it still comes down to writing great content; there is no substitute for that.  Then give credit to those who contributed to your knowledge base in developing that content.  Associate yourself with “authorities” and authorities will associate themselves with you.  There is no magic to becoming an expert … you need to do the hard work … you need to know your stuff AND you need to extend the knowledge of your readers by adding new facts, opinions and perspectives to drive home your points.

And to show that I eat my own cooking, please be sure to visit http://www.seomoz.org/blog/the-role-of-outbound-links for related information on Outbound Links.