Creating your own content network. In this method you have 100% control over link text which is good. You have 100% control over the industry type where your links are placed. The down side is it is hugely time consuming to create high PR sites for your market/industry and it is deemed just as black hat as link buying. The down side is it takes a lot longer to create and administer and is can be more detectable by Google than link buying. There is a huge amount of work involved in creating high PR sites (you still need links to these sites to inflate their PR) so that a share of this PR can be passed to your main sites.