Symphonic Choirs

Symphonic Choirs is a choir synthesizer produced by EastWest/Quantum Leap, able to recreate the effect of a entire choir for any song and is popular with indy muscians. It is however, extremely expensive, being one of the most expensive of the vocal related software synthesizers a Indy muscian can buy.

External
http://www.floridamusicco.com/proddetail~prod~symphonicchoirs.htm