Find blogs within your area of expertise and leave relevant comments. A lot of the time you can post your website URL along with the comment.
Offer to post for another blog. Typically they will allow you to add a backlink to your article in exchange for the article you write for them.
Article Writing and Article Sites:
Writing for article sites will generally ensure a backlink to your site as well. Just make sure that you change the wording if you want to post the same article on another site.
You can usually include your URL with your forum comments. The more informative and interesting your post, the better the chance it will be approved by moderators and the better the chance people will click through to your site.
Use your RSS feed. Submit your RSS feeds to directories that constantly update. This will attract the attention of search engines and help create backlinks.
Post an intriguing and entertaining video and you can create traffic to your website. People will also link to your site too.