I don't think that's really what you want. Consider the following:
1. If a source of traffic is free, everyone will have it, thus reducing the likelihood that it will be effective for anyone
2. The quality of traffic is more important than quantity in most instances. Try selling snow cones at an eskimo convention
3. Free is usually costly, but in time not money.
Take a look at this picture: http://i.imgur.com/MA3YeuX.jpg. That's how many weeks you have in your life if you're 25. Do you really want to spend 25, 50 or 100 of those dots getting traffic to your site?
If you can find out the lifetime value of a customer (assuming you do have a product) and make the leap to controllable (usually paid) traffic, you will have effectively taken the red pill, matrix style.
One of the most powerful traffic generating features is a blog.
The more indexed pages (centered around useful content, and strategic keywords) in search engines the more traffic your website will generate.
Make sure to pass 50 indexed pages from blogging as quickly as possible. Don't stop at 50. Continue the effort. The rate at which you'll see traffic increase will be based on the frequency of your high quality blogging activities.
Source: HubSpots state of inbound marketing report 2014