What other languages have first class continuations? Scheme does, some SML implementations do (smlnj has call/cc, IIRC), Ruby has call/cc* , anything else?

* But I've heard it's really not implemented for performance, and probably doesn't get used that much. I'm not really into Ruby, so...anyone?

Of course, you can do CPS yourself, though realistically you need first-class functions, tail-call optimization, and garbage collection or the extra bookkeeping will make it overwhelmingly complicated.