[byoung2]

Assuming you have not built anything yet, or are in the process of building, you could create a landing page that describes the idea. Start collecting email addresses for interested customers. Start running AdWords campaigns using relevant keywords to gauge interest in the product by comparing clickthrough and signup rates for different ad variations. If you are not sure what features are important to your users, you can run different campaigns advertising different features (e.g. "Electronic light beer - tastes great" vs "Electronic light beer - less filling") and track the success. After running a few campaigns you should have some data to analyze. If you have no interest (e.g. no clickthroughs, or lots of clickthroughs but no signups), you may have a dud on your hands. If you have lots of signups in a short time, you may have a winner. You can then build a prototype and ask people from your list to try it and give feedback.