The most effective methods: - Write and Submit Articles - Make a Newsletter - Join Online Communities and Forums
All the above, and I can also recommend creating viral ebooks branded with your business website to give away.
I have used quite a few methods, most of the popular ones for sure. PPC is great for a lot of markets, particularly ecommerce. However, SEO/Link Building and article marketing seem to do better for me for blogs.
You are talking about qualty traffic, right? Not JUST traffic. It's obviously not seo. I do ads, article marketing, word of mouth, submitting interesting content to sites, along with a few free methods. Mainly advertising and article marketing, though.
I have had best results with seo forums articles myspace there are some others I use too but they are not as effective as the methods I have listed above.
my favorite traffic method is stumbleupon have used seo, facebook, myspace getting into twitter, blogcatalog and soon technorati i have written posts about all the methods i have used to increase web traffic at http://www.traffic2mypage.com