Hi Chaps --
Thanks, Chris. Great minds think alike.

As to mic, I typically use a Shure SM57. Why? Because no one ever got fired for using an SM57.

I also have a pair of Shure PG81 condenser mics (which are probably out of production now).
Oliver, another possibility is to use multi-pads to play robotic voice phrases from audio. I didn't suggest this idea initially because it sounded like you wanted to play a melody/chords using a keyboard voice. There are tons of free robotic voice samples on the Web and that might be a source of musical material. The MusicRadar site has many free sample collections.
Hope these ideas help -- pj