Previously, I did some monitor calibration by eye using various test charts. I finally tried out some real calibration equipment (the Gretag Macbeth "Eye One Display 2"). Now, I know someone in the business of high-end color management who scoffs at all the consumer-level products. So my expectations are not sky-high.
Running through the wizard on the Easy setting turns out to be a snap. Just hang the mouse-like contraption over the front of the monitor, let the software flash different colors on the screen to be measured by said contraption, and it's done. Watching the software do a binary search with white and black squares to locate the sensor against the screen is kind of entertaining.
I read one review (ehhh, can't find the link now) that concluded that the Eye One Display actually was more accurate on the Easy setting than the Advanced one, so I left it at that. (Ran the process on new 24" iMac, old 15" iMac, and old 15" Aluminum Powerbook.) I can say that, subjectively, I do see some difference, with reds and blues looking a little deeper. The real test will be working with skin tones, gently graded skies, and high-contrast scenes.
My skepticism about color profiling comes from the fact that most color problems I experience are rooted in the camera (3x Canons). The S30 takes pictures that are a little too saturated. The G3 tends towards too much yellow in the color balance in any kind of tricky lighting. And The 20D oversaturates the reds (by about +15 in Photoshop terms) in any picture with big patches of red.
After a couple of days of use: I am actually seeing over-saturated reds now on the monitors, both flesh tones in news photos and solid red patches in GUI apps. The next test will come on Tuesday, when I'll have a couple of post-calibration images projected in the local camera club competition.