We also built something very similar, but targeting mobile users only. We started working on this app as an experiment on html5/cross platform apps; as well as to get server side experience supporting mobile apps.

https://itunes.apple.com/us/app/keyboard-shortcuts!/id489432...

https://play.google.com/store/apps/details?id=com.greenlife....

The traction has been low till now, highlighting the fact that we need to seek a lot of feedback and iterate on it.

(edited for formatting; first time poster)