NCH Tone Generator

This is a bit of a strange app, for pocket pc and palm, and desktop for that matter. Here's what their site says:

"Tone Generator lets you create audio test tones, sweeps or noise waveforms using your computer or a PDA handheld. The full features list of Tone Generator follows but if you have any doubt about its suitability a quick way to test it is to simply download and install it. You don't need to purchase to download and it only takes a couple of minutes to complete downloading and installation.

Typical Applications

Test tone generation in radio and other studios for the alignment of levels.
Calibration and testing of audio equipment or speakers.
Tuning music instruments as an accurate reference tone.
Demonstration of audio principles to students.
Acoustics testing and equalisation.
Quality control and testing of sound cards.
White noise generator
Audio band signalling.
Hearing tests (under suitable medical supervision).

Features

Sine wave, square wave, triangular waveform, saw tooth waveform, impulse, white noise and pink noise.
Supports frequencies from 1Hz to 22kHz bandwidth (subject to sound card).
Multiple simultaneous tones (1 to 16 tones can be created at the same time) (useful to create harmonics).
Mono or separate stereo operation (ideal to create dual tones or 'beats').
Tone Sweeps (Log or Linear).
Plays tone or saves as wav file."