Ask HN: How to get feedback on my prelaunch side project

So in the past I have spent months building a side project before showing it to anyone - this time I thought I would try and use the lean startup idea a bit more and have just built a landing page.

I want to use this to get feedback on the idea and see if it is something developers would actually use. My original plan was to post it to Show HN/Product hunt and I had hoped to get 5-10 people signing up so I could gather feedback. It seems these places prefer actually launched products rather than prelaunch ideas though.

What is the best way for me to get some feedback on my idea without actually building the product?

For anyone curious here is the launch page: http://preeli.com/