Virsyn has released BandShift which they describe as a Multi Band Frequency Shifter for iPad and iPhone. Here's the full story in their own words...
BandShift is a multi-band auditory filter and frequency shifter taking a new approach to manipulate the pitch of complex sound sources in realtime. The well know analog Bode frequency shifter shifts all frequencies in an input up by the same amount and thereby alters their harmonic relation and tends to produce inharmonic results. But it's perfect in dealing with transients and sounds smooth even with high amounts of down pitching.
BandShift splits the spectrum in 27 bands and applies a different amount of frequency shifting to each band emulating a harmonic pitch shifting. This gives you perfect pitch shifting for all kind of drum sounds over a vast shifting range of +/- five octaves without disturbing the transients or introducing metallic distortions. The extreme range of shifting gives you access to a vast field of unknown sonic territory.
The possibility to apply different shiftings on each band gives you exciting possibilities: Suppose you have a drum loop which is perfect, but the bass drum is a bit too high or too low to fit in your mix then you can easily get the bass drum shifted a bit down and the rest of the spectrum remains unchanged. But it's applications are not limited to drum sounds, they're only limited by your imagination.
Pricing and Availability:
$6.99 at the app store.