ASK HN: What web application do you need?

Hey,

I am an experienced web developer with some free time. I'm interested in some ideas for a web application, something you need that you can't find or is expensive. I'm willing to work for free following your specifications, in the end you'll get free access forever to the application. I was thinking about some application that will bring me passive income after is done.

Any ideas? :) Share your needs here, or drop me an email to hiulianro [@] gmail com