Why do we watch TV. Just think about it. Because there is something new every time we turn it on. If the TV just showed a static picture, you would never switch it on anymore. The same logic applies to your website too. There should be something different on your site every time someone visits it. So you should plan on providing dynamic content. Web 2.0 is one of the easiest ways to make your site dynamic. Add a blog with regular posts. Feature YouTube videos on your site and update them regularly. Add a forum to the site. Link your site to social media like Twitter and Facebook. Make it dynamic and you will give your visitors a reason to come back for more.
The only way to get repeat traffic is either by adding a service that they can use that brings them back or adding fresh, useful content on a regular basis. When I say fresh content, I do not mean an RSS feed from some other site.