Ask HN: How do I get potential customers to signup on my holding page?

We have recently released a basic holding page for our new product (www.imagexyapp.com) that allows users to signup to be notified when we release. What are the best ways for us to get attention that will bring in users that will sign up?

We have been trying the usual route of: - Social Media - Emailing existing clients/friends - Blogging about it on personal blogs and as guest authors - Sending out press releases

Please share any stories that have worked for you in the past, or any ideas you may have.