LSP Plugins: Oscillator plugin tutorial [hooktube]
This Linux audio plugin (I'm using it in Ardour) works as a simple vocoder for speech samples (or any sample). The chosen clip in the demo is "Hello, this is Linus Torvalds and I pronounce 'Linux' as 'Linux.'" Prepare to hear it in a zillion metallic renderings.
Thanks to hooktube -- while it lasts -- for allowing users not to have to link directly to [Eric Schmidt's company] should they so choose.