http://www.celemony.com/

Melodyne from Celemony IS the coolest application in audio editing or will be when its released.

The idea is to be able to record or take a recorded clip of a person singing or a musical instrument and be able to change or Correct a note.



The website writeup is as follows

Melodyne is the perfect tool for pitch shifting and time stretching in convincingly natural sound quality, for correcting the intonation and timing of singing, for audio quantization, producing harmonies, and remixing and restructuring the melody, tempo or timing of existing recordings. With Melodyne you can actually do the impossible — and do it easily. Melodyne is intelligent: it recognizes the music in an audio file and represents it directly as notes; in this way, it offers highly intuitive and far-reaching access to the musical material and permits a sensationally flexible and creative way of working: with Melodyne, the music is in the foreground, not the technology.

Melodyne comes in four versions for Windows XP, Windows Vista (32 bit) and Mac OS X — from the single-track Melodyne uno and the ultra-flexible Melodyne plugin to the multi-track Melodyne cre8 and the comprehensive Melodyne studio, with which you can edit any type of audio material and even entire songs. You can integrate all Melodyne versions into your production environment via ReWire, VST, RTAS or AU.