Here is something that I did in a few minutes.  What you hear is a drum loop, in which I hummed a bass line  over it ( I discovered that humming is best for a bass line).  I converted it to midi, and chose a synth bass.  I did this by choosing the "Melodic, " algorithm, which is what you should choose for a bass line.  Then I chose the "Polyphonic," algorithm on the same hummed piece, which I saved as midi, and used as the third track.  As you can see it created all these other notes, to create a fun little piece. 
 
http://www.calfcomusic.com/MeloDyneMagic.mp3

That is amazing! Nice job!!!

Very nice! I have only been exposed to Melodyne because of X3 but have been having a lot of fun learning its capabilities and limitations.

I keep being amazed by Melodyne (and the ARA integration). Like the OP, I hummed a bass line (and my humnming is iffy at best!!), dropped it into a track with Cakewalk SI bass, and it all worked beautifully. In the same song I also had noticed that in one bar I had played a major chord instead of the intended minor...edited it in Melodyne Editor, moved the "offending" note a step down, and bang done. The song in question (un deux trois) (just hit the play button on the left to stream):
 
http://www.nimbitmusic.com/michstar/#home/seizetheday
 

S.L.I.P.
Here is something that I did in a few minutes.  What you hear is a drum loop, in which I hummed a bass line  over it ( I discovered that humming is best for a bass line).  I converted it to midi, and chose a synth bass.  I did this by choosing the "Melodic, " algorithm, which is what you should choose for a bass line.  Then I chose the "Polyphonic," algorithm on the same hummed piece, which I saved as midi, and used as the third track.  As you can see it created all these other notes, to create a fun little piece. 
 
http://www.calfcomusic.com/MeloDyneMagic.mp3

cool, I will check out your song later at home. I tried to sing a bass line, but failed big time.  Maybe I should try humming...!

S.L.I.P.
Here is something that I did in a few minutes.  What you hear is a drum loop, in which I hummed a bass line  over it ( I discovered that humming is best for a bass line).  I converted it to midi, and chose a synth bass.  I did this by choosing the "Melodic, " algorithm, which is what you should choose for a bass line.  Then I chose the "Polyphonic," algorithm on the same hummed piece, which I saved as midi, and used as the third track.  As you can see it created all these other notes, to create a fun little piece. 
 
http://www.calfcomusic.com/MeloDyneMagic.mp3

 
I only now picked up on the fact that you picked polyphonic on a monophonic source...interesting! Will try that myself too!

Yes, that was the real magic, turning the mono humming on the third track using the polyphonic algorithm.  I could of done some editing on the notes that were a little off, but I wanted to show the speed of doing this as well as the results of thinking outside the box.

Ha I have done that "run a monophonic line through the polyphonic algorithm" thing too. The results are hit and miss....sometimes it doesn't make sense, sometimes you end up with something good that you never would have come across otherwise.