the author of this app says:
Tonetable is an application for DJs who want to control their digital vinyl system from their iPhone or iPod Touch. It produces a control tone that is compatible with most digital vinyl systems such as Serato's Scratch Live, Native Instruments' Traktor Scratch, M-Audio's Torq, Image-Line's Deckadance and many more.
Tonetable features a large scratching platter that allows you to scratch and throw the virtual vinyl similar to using a real turntable. To use Tonetable with your DJ software simply connect an audio cable from the line out of your iPhone or iPod Touch to your audio interface's line in.
- Scratch, throw and pitch bend.
- Pitch slider capable of fine pitch control.
- Configurable control tone (1 kHz - as used by Scratch Live, 1.2 kHz - as used by Torq or 2 kHz as used by Traktor Scratch).
- 33 or 45 RPM modes.
- Requires iPhone OS 3.1.3 or later.