Generally I've avoided Photoshop plug-ins. I've tried to do things 'the
hard way' in order
to learn Photoshop. Correcting color casts and manipulating specific colors
are two
things I've found to be challenging using just Photoshop.
ICorrect has become a vital tool for me for assuring that the 'neutrals' in
an image
are indeed neutral.
I think of Color Mechanic Pro (http://www.colormechanic.com/ from Digital
Light &
Color) as the counterpoint to ICorrect. Color Mechanic is excellent for
making modifications
to explicit colors in an image.
-JimD