I built Guitar Charts Creator for myself, as it was a tool I had been wanting for a while on my tablet. GCC is a tool for guitarists, allowing them to create their own chord charts, designed initially for the iPad and available on the iOS App Store.
I built the app in HTML5 using jQuery Mobile and Backbone.js. Later, I ported GCC so it could run as a stand-alone, traditional web app (via Heroku), as well as porting it to OSX via the Mac App Store (using PhoneGap).
All versions of GCC use Parse.com as a backend “cloud” database, allowing user data to be synced between any version of GCC.