I think this discussion can be now heavily debated after many search engines have brought in methods to penalize web sites for selling text links.

The best way to gain free text links is simply by registering on article sites and writing your own articles submitting with a link to your site. You may also promote on forums.

It is also required that you achieve quality back links as these will allow better ranking results. One way links are always best way to achieve the high quality rankings!

A large number of other factors pay roll into achieving those quality back links!