I've had great luck using a mix of manual back linking, using blog carnivals for backlinks(not as effective as it was a few years ago), and automated backlinks, usually through private blog networks (Linkvana, SEOlinkvine, etc.). Article marketing still works to build backlinks too, although it also has lost some effectiveness, and is better utilized as a syndication based traffic builder.

The best traffic builders are the backlinks that get you both: traffic and SEO juice. I've gotten links from big sites, like the Wall Street Journal and the Washington Post, and let me tell you, it worked wonders. Even if links from the big sites are no-followed, as many are these days, you still get a solid SEO benefit from it according to many SEO experts.