Hi all,
Just had to remove a yellow cast from a photo. I find this method easier than using the colour balance, and it seems to work on any colour.

In CS3 or any version(that has layers and blending modes) as far as I know.

Duplicate layer
Apply Blur>Average
Change blending mode to soft light.

EDIT- CORRECT STEP ARE: (see Dbax post below - **RICK**)
Duplicate layer
Apply Blur>Average
Ivert( image>adjustments>invert)
Change blending mode to soft light.

simple as that,can be made into an action so its a one click fix

Thought I'd share it and ask for feed back
David