@OP, when it comes to link building... thing in terms of your right to do marketing of your website. You have the right of marketing on relevant blogs and appear as a knowledgeable guest poster, you have right to participate in relevant forums, doing blog comments on related blog posts, advertising on local magazines, classified sites, write your mini-books & tuts (PDFs, Docs, PPT) and share them with people on the sites which are meant for it, make your podcast, videos and publish on the sites meant for them, needless to mention... you have right to operate your channels of popular social media sites, and so on.
This is the key of all link-building decisions and doing it in the right way. Hope this helps.