Interestingly I was working on this as well. It was called "should I Build it?" and the idea is if enough people vote YES (you decide how many people are enough), then you build it.

Two Additional Suggestions:

1. After the potential user votes "yes" or "no" allow the idea author to collect feedback as to why they voted the way they did. (customer development built-in). This will provide some great insights into what's valuable to your prospects.

2. Secondly it will be more useful to allow the idea author set this up on their own domain and be able to add their own styling to the page because most of the traffic the page will get will be from the idea author's network.

I don't see myself as a user, coming to your website to look for ideas to support with my email.

Finally how do you plan on monetizing this app? This is the chief reason I dropped the idea which is probably short-sighted but it'll be interesting to see how you go about it.

Good Luck.