Everyone talks about ways to build traffic. From paying for it directly with money for PPC, banner ads, text ads, paid links, paid reviews (hardly seems impartial, does it?), and CPA networks.
Then there’s the bum marketing methods such as Article Marketing.
Then there al the supposedly “free” methods; such as social bookmarking, social networking, and “product placements” in rich media, like YouTube videos, Software Download sites (PAD files), Podcast libraries, webinar libraries.
Other traffic icons could be auction sites like Ebay, Craigs List and in the good old days, WikiPedia, DMOZ
And we can’t forget RR/MLR/PLR marketing, where a product (like an ebook may be given away free, with resale rights included, in order to attempt to create a viral word of mouth campaign, based on giving free quality content, on the “assumption” that they will ultimately come back to you for more quality stuff, but this time “pay” for it. Hmm 
But perhaps one of the most interesting of free methods, is affiliate themselves. An army of hopefuls who will promote your product in order to make commission. They find their own leads, pay for their own adverts, you just give them a cut. Hmm.
Of course the “power affiliates” become “JV Partners” as they have large lists of 1000′s of people. So getting them to promote your product can be a gold rush. But of course these people are busy, and swamped with offers from Johnny hopeful. So they tend to only promote their own network of “guru buddies”. Sigh.
But the tried and tested method, still remains as “backlinks”. Where another (related) site thinks you are worthy of a link back to you. It’s like a silent endorsement or “vote” at the same time. And if the originating site has a high value (high PR, authority status, or highly indexed itself) then that “vote” can count highly. In the eyes of search engines like Google, this still has great significance.
More to come…