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The LensAlign Pro is a $140 system that basically offers a plane on which you focus your camera's lenses and a ruler, tilted back at an angle, so that you can measure how much your camera front- or rear-focuses.

I've borrowed one from my buddy Josh (as I suspect a lot of people will be doing for $140), and I'm happy that most of my lenses - in a very quick-n-dirty test - seem to focus just fine. The 70-200 f/2.8L IS required the most correction. I set it in-camera to about -4, but having viewed the images on the computer, it's obvious it'll require a bit more.

Unfortunately, the LensAlign does a great job of exposing (no pun intended) some of the flaws in some of the cheaper glass out there. These images come from my 50mm f/1.4 lens (right image) as well as the 24-70 f/2.8L. I would expect the purple fringing on the 50, but I'm a bit dismayed at the performance of the 24-70. I'm not overly disturbed, however: it's rare that I shoot strictly black-and-white objects in harsh sunlight. 🙂