As I mentioned in the previous post, a burried link is just that, burried. If you can’t find your link on someones site, neither will a visitor.
All that is required to increase page rank is to exchange links with a related site that has a higher page rank. Optimize a site and get some good content and a decent pagerank will naturally follow.
Like Dom said, link to sites google is penalizing and you’ll eventually get penalized as well.