Signal Inspector is a basic signal generator and analysis tool. It features an oscilloscope, a spectrum analyzer and a spectrogram, plus tone, noise, and pulse generators.
FARMER TIM Quite a useful tool for anyone working with audio. The log/linear frequency display toggle doesn't seem to work in the spectrogram, and there's a greyed-out "Sampler" button, but it's early days yet. (Version 0.3d)