reciprocal link: Post around on forums asking for reciprocal link exchanges, but yet again be warned on your selection.
Join Yahoo Answers: Providing useful answers, along with a link is an easy way to earn a back-link. This method is explained in detail in one of my posts on Marketing your Blog on Yahoo Answers.
Guest Posting: This is the very popular way, specially between bloggers on the internet. Guest posting is not just about getting the backlinks.
fellow bloggers: Contact your fellow bloggers in your niche and ask them for an reciprocal link exchange.
Digg: Submit your voice on Digg – First build a solid profile, where you have a network of loyal diggers.