What king of application would you develop if you would be a developer?

As a developer with 8 years experience in software and web development, I work with programming languages like c# and JavaScript, i use Microsoft .NET Framework and NodeJS. I write applications for all platforms including windows, linux, ios and android  and successfully doing this for a long period of time.

I use bitcoin on a regular basis, watching it from 2010 I love the technology and already write a chrome wallet app for personal use, now I thinking what my next application should be.

If you have any good idea about bitcoin or other altcoins I can develop the app and share the revenue with you.