Anything that makes a major or minor chord (8/12 is my favorite!) It'd be super cool, (yet I'd question the effectiveness) if you could make a jazzy chord with an electronic siren (Bbmajor7 would be super cool, since all you'd have to do is add a 440hz (A4) tone to B flat (465hz) and F (700hz). Basically, A P-50 plus 440hz)
"... Sometimes moving against the current is as easy as going with it... "