MashTactic mashup tool! From QuikQuak audio plug-ins.

MashTactic is a plug-in that can separate various parts of a full audio mix.
Many sounds, include vocals can be cut or isolated from a track.
* A great tool for mashup music makers.
* Can be used as a sharp cut-off filter, as demonstration in this video.
* MashTactic works on transients, allow the user to emphasise and cut percussive sounds allow control over punch of drum tracks.
* Great for analysing stereo spread and mix of a track you're composing.
Coming soon to: http://www.quikquak.com
-Quik Quak