When considering external links one has to take into account Search Engine Optimisation. Reading this post, it may seem like common sense, but it is good to keep this sort of thing in mind when you are creating these links. When search engines crawl your site, as you know, they read the text on your page to see what the content is about so they can reference you correctly in the SERPs. This can be beneficial if done correctly and damaging if not. Spending some time thinking about what sites you want to link to will help ensure your site will get the best chance in moving up through the rankings.