You can do forum posting, blog commenting, article submission etc for seo purposes which helps to getting traffic to your site.
One of the best ways I know to get traffic...and not just traffic, but targeted traffic, and that's really the kind you want...is to do guest blog posting. Find related blogs in your niche that already get a lot of traffic, and give them what *they* need the most...content. Contact the blog owner and offer to provide them with a good, high quality article in exchange for you being able to leave a link to your site in the article. It can take a bit of effort...but it's some of the best traffic you can get and it doesn't cost money.
Here are 5 things you could do: 1. Buy traffic 2. Buy expired domains with traffic already going to them and forward the domains to your blog/site. Make sure it's relevant or else this is a waste. 3. Upload videos as Goodboy mentioned above. Be sure you use your own content or at least get permission to use other peoples content. 4. Hire an SEO company to get you ranked page 1 on the major search engines for at least 3 of your top keywords you are targeting. 5. Build a huge presence with Social Media. (Twitter, Facebook, Stumble, Google +, etc)