1. Submit to directories
Listing your site in a directory, web users will view your page as a reliable resource that fits their search criteria.
2. Write to webmasters and compliment their web site
They may include your kind statements into testimonial section, and link back to your site.
3. Submit articles to article directory
This allows people to read your work and publish your articles for free. Make sure to include a biography Box that link to your site.
4. Making use of blogs
The blogging community is keep growing, and blogger are always looking for new things to post on their blog.
Talk to other bloggers about links and posts about your website.
5. Post comments in discussion groups and on message boards
Post useful and relevant comments on discussion groups or forum. Remember to add a link to your website after your comments.
I read an article recommending submission to not so popular sites in order to get various links.