Original author, DrPetter:
What I present here is, if you will, an MS Paint for sound effects… or something along those lines. It’s meant to make it dead easy for anyone to whip up a few simple sound effects and save them as .WAV files for playback using most game/media libraries like SDL or pygame.
Basic usage involves clicking the left-most buttons to automatically generate random sounds loosely targeted at certain categories. For more advanced users it’s possible to spend some additional time to manually create fairly varied and interesting sound effects.More here.This is a port of the Intel-only, Leopard-only version by
timdoug. Since the original version was heavily Intel-centric (and little-endian centric), I added code to allow PPC machines to export WAVs and load & save settings files. I know I'm not the best programmer, but I tried. I really hope I didn't introduce any subtle bugs.
I only have a G4 running Tiger, so that's all I was able to test it on. However, this version is PowerPC only. It might run on Intel Macs in Rosetta, but I don't really know.

Download:
sfxr.appXcode Project