ColorThink is very useful. You can also examine a number of things with carefully constructed imagery.
A Granger Rainbow can illuminate all kinds of interesting things in a profile from hue shifts to reversals to banding to sharp drop-offs.
A 3-color gray ramp is good for viewing neutrality, banding, and where color-casting might occur. You may end up finding problems with your monitor profile, too.
Color ramps are good for observing gamut compression.
GMG has a TIF file, if you can get hold of it, called the CMYK_smoothCheck that can shine a light on all kinds of things, too.
I know Measure Tool works with Mac OS X, I am not sure Heidelberg software does....
Hi stargate,
Correct, it is Windows based only but also offers a bit more functionality such as Gray Balance Optimizer for calibrating to near neutral plate curves.