Making sheet music out of untimed hand played and piano roll midi files
If you look at my profile and scroll through the scores, you'll find that I have made sheet music out of player piano rolls and hand played midi files that I didn't play to a metronome.
MuseScore has an algorithm of some sort that can find the approximate tempo of a midi file and quantify it to that tempo (though the software will remove syncopation and mess up grace notes). I use this to my advantage to make piano roll transcriptions, and sheet music of my own playing.
Unfortunately, the program has a terrible time mapping swing in midi files (especially foxtrots from piano rolls) and I usually have to quantize everything to an 8th note or 16th (depending on if I use normal tempo or double time).
This method is very time consuming and I wish there was a way that the program AT LEAST WOULDN'T REMOVE SYNCOPATION!!!! Correcting the removed syncopation is the most time consuming part of the process.