Internet is full of the folks seeking freebies. You know all was started with free e-mail, free Greeting Cards, and much more free.
Freebies providers get a ton of free traffic and convert this traffic into money sometimes by selling advertising space on the site and sometime by getting more sales.

To take home lesson is

Offer some sort of freebies related to your website and submit it to freebie directories, like Download.com and many more other freebie sites.

You have nothing to offer free? Here are some ideas to create one freebie quick… Offer an ebook or report, or if you are selling ebook already, offer some free chapters…
You can offer an e-mail course. Or some templates useful for your website users.

If you are planning to have much viral free web traffic, do use this tactic as soon as possible. Folks will be coming to your site in lots.