What is the best way to get free advertising for my site?

Article Marketing

You can try article marketing, contextual commenting on blogs...(Not just spam, but meaningful and contextual comments), commenting on forums and contributing to discussions with the URL in your signature. Some search engine optimization would not hurt as well since search engines are the best place to get traffic from (the main purpose of advertising is traffic)
Social networking tools are also being aggressively used by internet marketing people to popularize their websites.

Article marketing, social networking sites, blogs, bookmark, web 2.0

You can also use videos and post them to youtubes. Use podcast directories also for even more traffic.

Hi Tod,

I wrote an article on my blog some time ago on free marketing..check out my signature and perform a search on free traffic while your on the blog...you may get some good ideas.

If you don't have a budget right now to spend on Pay-Per-Click campaigns etc - then your best option is to go with Bum Marketing methods which really just means free marketing...

You can submit articles to the major article directories like EzineArticles, ArticleBase, etc. Make sure your article is of value and that it makes sense and also make sure that you include your targeted keywords in the title of your article and also on the first line of your article.....this way the search engines quickly realize what your article is about and places them on their index accordingly...

Sign up to forums in your niche and contribute to the forum with valuable post and make sure to include your signature on your profile so that you can drive traffic to your site from the signature section of every post you submit to that particular forum....

Make sure to do some keyword research at first, so that you know which is the best keyword to target, one that does not have so much competition.

send an email to bloggers/social networks that have large followings and tell them about your site.

this assumes you have something worth talking about

Press releases - hands down.

Articles writing using Article Post Robot. You can get a 7-day free trial. Make a good keyword research and 3% keyword density.