Rangana Herath has a carrom ball, and I think for a while Pragyan Ojha had some semblance of an "other one", but no leftie international spinner aside from those 2 has one I don't think. I personally don't feel that a SLA bowler really needs one at the top level, because as a general rule they will turn it big enough for the arm-ball to be a big threat. At a lower level I think it is a useful tool, because people don't always read it well from the hand, and I've been working (for a few years now) on one that is flicked out like a carrom ball, and against lefties it is almost like bowling a leg-spinner, turns away nicely. But my biggest wicket-taker is the one that skids on, normally I get it to straighten (and turn away a bit) but the one that kicks on is just about the biggest wicket-taker.
And 100% with what Fattus says, the control needed to be a chinaman bowler (if only purely because it isn't as effective to right handers) is ridiculous!