Capo is an OS X music analysis app which musicians can use to very rapidly figure out melodies, chord progressions, and bass lines from mp3s. I went to the web site, watched a couple demo videos, downloaded the demo, and had extracted a melody all in a matter of minutes. The videos use guitar rock for the examples but I analyzed dubstep with it. The app assumes you're using a guitar, and while my background in (very basic) guitar made it easier to use, I don't own a guitar these days and that didn't slow me down at all.
I cannot recommend this app highly enough. Words do not exist suitable to capture and contain its magnificence.