How do you get people to know about your new app with no contact and how do you get content traction at the initial stage of a web app? I'd like to believe in 'users will come along if your app is good enough' but it will never be good enough if no one knows about it.
Give it away free to reviewers?
Hold a contest to give away 100 copies/licenses/subscriptions?
I think that there are different paths depending on whether your app is for consumers or business.
If you're targeting business users and you have not been spending time building your network now is the time. I'd start with linkedin, searching for groups that include the kind of users you are targeting. Join the group and try to meet some of the people that could be your users. You can then use that network to try and get users and build some reputation for your application.
Once you have people in your network see if they can point you to the people that are influential in your targeted community. You can then contact them and pitch your application to them and see if they will help spread the word.
I guess Jeff covered it above but the best way is through social media marketing. Brands, products and trends are controlled by media contributors and online influencers such as bloggers, reviewers and digital creators. They are the ones that lead conversations and shape opinions. http://bit.ly/4JFD3E