1. Start a Blog–This one is probably the most important of all 10.  Setting up a WordPress Blog is relatively easy to do and is free.  Blogs are a great way to build a presence online and once established can drive a lot of traffic to your site if done right.  (If you need help with this check out this Blog post for a free step by step guide)
2. Join a few forums–related to your niche and get involved in the conversation.  Don’t try to sell just meet new people in your niche and network.  Most forums will let you have a link back to your site in your signature line.
3. Comment on other peoples Blogs–related to your niche.  Take the same approach as the forums—don’t try to sell just leave relevant comments and be helpful.  You usually can leave a link in your signature when you comment also.
4. Write a few articles–related to topics in your niche and submit them to article directories like ezinearticles.com.  Your articles should be helpful and informative–not a sales pitch.  Then at the end of the article in the resource box you will have a chance to give a little bio and leave a link to your site.
5. Link with other sites–that are related to your niche.  Ask them to link back to you.  Try to find sites that have a page rank at least the same as yours and higher.  The higher the page rank the better when choosing links.  Make sure you are linking to sites that are relevant to your site and are helpful resources for your customers and be sure to get them to link back to you.
6. Join YouTube–and make a quick video about your business and what you have to offer.  You can link directly back to your site from the video page on YouTube.  YouTube can be a huge traffic source if you get a video that people like.  (For more ways to use video to promote your site check out this blog post)
7. Join Twitter–Building a following on Twitter is relatively easy once you get started.  Just find other people on Twitter related to your niche or people who may be interested in your niche and follow them.  Most of the time they will follow you back.  There are also other tools you can use to get more followers on Twitter quicker like Mr. Tweet.  And remember don’t make it all about selling–you need to be interesting, informative, and helpful to keep people interested in what you have to say.
8. Join FaceBook–FaceBook is similar to Twitter in the matter that you should find people to follow with similar interests that will be interested in what you are posting about.  I use my facebook acct to find old friends that I grew up with and have been amazed at how many friends I have caught up with.  **And have made a few sales along the way.  You can also link your Twitter account to your Facebook acct so everytime you post on Twitter your post will show up in your Facebook acct.
9. If you followed step #1 and you have your Blog set-up–then join some Blogging Communities like BlogLog and BlogCatalog.  These sites allow you to follow other Blogs and other people to follow your Blog.  You can also have it update your acct every time you have a new blog post.
10. Join some social bookmarking sites like StumbleUpon, Technorati, and Digg.  When someone likes your blog post they can Digg it or Stumble it so others can see it to.  The more that is done the more you will be noticed and the more traffic you will get.

These 10 ways for free traffic are just a starting point.  Start out getting these things implemented and use them often and you will definately see an increase in traffic and will have done it all for FREE!