Have you ever had to come up with a melody line for a song intro, but weren't inspired to make something up? I play the violin for the Surrey 1 Couples For Christ music group, and there is never violin sheet music for the songs that we play. If the song is on YouTube, I can write down the lead guitar part. But if not, then I don't know what to play, and I'm not always good at creating something from scratch.
So what I am trying today is the Melisma Stochastic Melody Generator from Carnegie Mellon University. Enter the key and whether it is major or minor, then press "Generate Melody", and you will get a midi file with a generated melody.
Here is an example you can listen to.
Then, if you read sheet music, you can use a MIDI to sheet music converter. I haven't found a good one yet though.
A good way to turn your midi file into sheet music is to download ScoreCloud, choose to Record, then play the midi file using QuickTime. You get simpler results by recording with your microphone than importing the midi file, which produces a messy result.