I made a quicky little tutorial showing how to distort your voice and sound like a robot using two free open source programs. At first it looks a
little complicated, yet it's simple-stupid. (More or less turning dials.) I find it fun to play with.
The ones I'm using are LADSPA FX, I think there's a way to use them with Audacity, but I find it a lot easier to use them with LMMS. (They're
bundled with the software.) Also despite having "Linux" as part of the acronym, there's a Windows version and I believe an older version of the
software has been ported to Mac.