However, I'm assuming what you really want is users/conversions. In that case, you need to think about your project/site/business as a relationship between 2 parties with the internet simply being a more scalable medium for communication between you.
To get people interested in a product/service, it has to fix a pain point, be really interesting, or you have to be the best. You can "be the best" by showcasing your knowledge of the problem with blog posts, interviews, helping people out on forums, and becoming involved in communities that would be in your target demographic (forums, meet ups, irc groups, etc).
Fixing a pain point or being really interesting is a product /market fit problem so if you've shown your site/product/service to a lot of people and it's not sticking, you need to do in-person interviews to figure out what's not good enough.
In general, if you're trying to build up traffic, that's really building up a community of people (who are the source of good traffic) so you need to approach that in the same way you'd build up a community offline: be interesting, be a good community citizen, and give without asking much in return.