CD-ROM / ISO Emulation (Free Program Suggestions)

Hi Gang,
I remember there being a freeware and or open source program that could emulate CD-ROMs and I think DVDs too. I think it was called waste, or some other unusual name. Perhaps it was an acronym. I'm specifically interested in freeware and open source solutions. So I would have to say that rules out Alcohol 120% and the like. Can someone refresh my memory?
Thanks in Advance,
Christian Blackburn

Daemon Tools by any chance?

Hey Thanks Ross. That's exactly what it was .
Cheers,
Christian