Adobe Audition.
It's the only program out there that allows you to digitally stretch and compress wave lenghts. (via time component)
there's lots more to it, but that's just the basics.
If you wanted something to mix live with ... like a dj console:
Traktor's DJ Studio.
If you had turntables and a mixer ... but are SICK of buying vinyl
http://www.rane.com/scratch.html
this thing is the shit.
use the laptop to feed songs into the Serato hub
the Serato hub feeds data to your exiting turntables
and you have intant vinyl control over MP3s.
no more record crates, no more cds ... just a laptop (and pray to god it doesn't crash)
check the demo
http://www.rane.com/SeratoScratchLive_High.mov
absolutely no pitch control.
You can do the same thing using Traktor's DJ Studio and a laptop.
