Without a doubt, the Electro-Harmonix Talking Machine would take the title of "Best Theremin Effect" for 2012 (if such a title existed).
Here, you can hear Rob Schwimmer using the 'Machine in a performance of Kurt Weill's "Lost In The Stars". That's not a human singing the melody; that's Rob's theremin running through the TM's vocal formant filter!
It's uncanny how much this pedal sounds like a human voice. Originally designed for electric guitarists, we believe Peter Pringle was the first to bring it to the attention of thereminists earlier in the year with this video he posted on YouTube. Since then, we've seen several more thereminists experiment with them.
Some purists will argue a theremin needs no effects... that it's almost mechanical simplicity stands on its own. For others, combining the magic of the theremin with the uncanny vocal tones this pedal can produce elevates the theremin to a whole new level.
So, which side of the fence are you on?