Ask HN: 150 beta signups – what should I do next?

I recently thought of an idea then quickly set up an invitation page.so far, approximately 140 people have signed up, this is beyond my expectations as i thought that only about 20 or so people would sign up.I really need advise and suggestions on what to do next.I would like to know whether this is a sign of something that could become a business opportunity for me. Thanks.