I was exactly wondering about the same thing. Are you talking about something like in "Dumonde - God Music" when the slow part hits and the males voice comes in? I would also be very happy to find out how to achieve this effect.

this is really easy to do

get your vocal in a wave editor (sound forge etc), reverse the whole sample, put a reverb on it with lots of decay, and then reverse it again.

^^ what he said. This is very easy to achieve.

___________________
"When I read about the evils of drinking, I gave up reading."

you can also put some delay on the original sample then reverse it and add the reverb...its sounds cool...but don't over do it with the delay.

get this effect by using an impulse response reverb, you will have the option to reverse the impulse waveform.

SIR is a free one here: http://www.knufinke.de/sir/index_en.html

some of the pay ones are Waves IR1 and Voxengeno Pristine Space

___________________
bobday//tdh

Another good reason to love Reason's reverb

___________________
Latest releases:
Endless Cycles [Capital Heaven]
The Charlatan [Morphosis]

If you can get ur hands on logic, the enverb machine has a lovely preset for reverse verb

___________________
Siberian Sun "Forstbite" - Dedicated
Fred Baker "la parts des anges" Siberian sun remix - asot
Nautical Imagery "distant Dreams" Enhanced Recordings
Mannix -v- Kaymak "World gone mad" A State of Trance

There was a tutorial within an article in, I believe, the august issue of CM; check it out if you can.