I make $300-$500/mo. with http://www.makecupcakewrappers.com

I started it three years ago with a single web page and an email-me-when-it's-ready form. I barely got enough emails (50-60) in the first couple months to justify moving forward. But I did, with three designs and a simple design-by-form interface. Fast forward to today and I have dozens of templates and a custom drag and drop interface done in canvas. I have a pretty good conversion rate given that I only get ~90 uniques per day.