I've wondered if reversible computing research has had any real world impact. The theory is it would reduce heat since you're not increasing entropy, but I wonder in practice if that has ever been useful.
All the experience I had was theorem proving for crypto apps - that said, I think there is only the appearance of reversibility at the symbolic level, underneath its the same old mess - I vaguely recall that at full tilt, the room with all the Suns would get quite toasty . :-)