By offering FREE information or product, you are getting the attention of the Internet community. It is like the sample or freebies that magazine or are giving out to increase circulation. It is the marketers' method of "A foot at the door". Once they find your site interesting, they will come back again to visit your site (increase traffic), tells others to visit your site (mutiplying effect) and perhaps buy from you (if you are offering other products).
If you want to increase traffic, offer some freebies on your blog or site.
-Write good content to give away free (basic)
-Create your own product and brand it and give it free is the best way to go (i am in the midst of doing so, this method requires time).
-If you don't have your own product, you can also join an affiliate program (you have to do your won research and choose wisely)
Note: If you have a blog or site that offers the above traffic methods, i would love to interview and feature you as on my blog as success stories. Please email me or leave a message on my chat box. Cheers!