The best technique I used to get free traffic is to write down Good content and to run a Search Engine Optimized web site
No, seriously, I don't really know of any free traffic program that seemed interesting to me. I mean, it's personal and I did never try any, but I found the principle a bit odd.
Actually, how will you tell the visit you got from such program where true visits and not automated ?
And what do you give back to participate ?
It's useless to me if you have 1000 unique IP connecting to you web site everyday but none is going further than a page load and no post no clicks on adds no registering ...
I did not elaborate much on this so far, but to me honest SEO and good content is the way to success.
If I'd try to simplify my views on SEOing I'd say three things are really important :
1) content : Far ahead, content is always what will make you show up in search results and will tease users in the end.
2) Links : Meaning Internal and external, thus mod rewrite, xml, Html sitemaps and Backlinks. This is where we can make it a lot faster (Indexing and PageRanking) and win time.
3) Code : Meaning, your site's coding, how efficient, how nicely, and how fast. This is crucial, your site must load ok on most browser, be nice and unique and load pages the faster possible. Anything above 5 sec is a nightmare here.
This will lead to true user visiting, and enjoying your site. This can be longer than free traffic programs to get traffic, but it will be true traffic for sure
Then, I must be wrong, there must be some interesting programs
But one cannot rely on just this for a web site success, this can just be a plus IMHO, not the main effort we put in a web-site.