Piano was very prominent on Rolling Stones cuts. Who all played piano
with the Stones?

Ian Stewart 1963 - 1985
http://en.wikipedia.org/wiki/Ian_Stewart_(musician)
He is listed as a past member of their band:
http://www.stones.net/band.htm

Chuck Leavell 1989 ~
http://www.chuckleavell.com/stones.html

Nicky Hopkins (session pianist) (played for some albums)
http://en.wikipedia.org/wiki/Nicky_Hopkins

There are others that have played piano for various tours and albums,
but Ian and Chuck were the most prominent.

If you require any additional information please post a request for clarification.

Thanks!

Other contributing keyboardists: "soul musician Billy Preston, Phil
Spector and Neil Young associate Jack Nitzsche and Ian McLagan of The
Faces."

http://en.wikipedia.org/wiki/Ian_Stewart_(musician)

Billy Preston (died last month at 59):
"After the Beatles, Preston played keyboards for the Rolling Stones,
alongside pianist Nicky Hopkins. Preston appears on the Stones' albums
Sticky Fingers, Exile on Main Street, Goats Head Soup, It's Only
Rock'n Roll and Black and Blue. He toured as a support act with the
Stones in 1973 and recorded his live album Live European Tour 1973 in
Munich with Mick Taylor on guitar."

http://en.wikipedia.org/wiki/Billy_Preston

Jack Nitzsche (died in 2000): 
"While organizing the music for the T.A.M.I. Show television special
in 1964, he met The Rolling Stones, and went on to contribute the
keyboard textures to their mid-sixties hits such as 'Paint It Black',
and the choral arrangements for 'You Can't Always Get What You Want'."

http://en.wikipedia.org/wiki/Jack_Nitzsche

More on Nitzsche from "Turning the Key of the Universe: Jack Nitzsche
Remembered," by Andrew Loog Oldham, manager of the Stones in the 60s:
"There are three keyboard players on those mid-?60s Stones RCA
sessions. If it?s a blues figure, it?s Ian Stewart playing piano (Ian
Stewart was the Ur-Stone who was not to become part of the group). On
a few occasions when it?s slightly strange it might be Brian, but the
rest?all the piano, organ, harpsichord playing?plus the denseness, the
body, the glue?is Jack Nitzsche."

http://www.gadflyonline.com/8-27-01/music-turning.HTML