Songify, by Smule.
Modifies your speech to a song.
Are you a bathroom singer, who doesn’t sound good elsewhere?
Speak into your phone, the app tweaks your pitch, and adds a track to make a melody.
It has a simple interface, and you can always re-songify with a different tune.
Sadly, it doesn’t have editing tools for better results.
Can’t say much about musical career, but it’s a whole lot of fun.