Thanks for the feedback everyone. I too use Mac's. I do most of my post processing on a 20" Aluminum iMac that's about a year old. I have thought about it, but never calibrated the screen. I do notice that when I look down from above on the monitor the sky does have a slightly greenish (very slightly) cast to it. But when I lower my angle of view the sky looks perfectly sky blue, a light sky blue. Interesting phenomenon.
Anyway, thanks again for the feedback and comments.