OK, now, I'm not too much about reinventing the wheel, but this is cool.  Not only does X-Rite give you a nice little ColorChecker, but they give it to you in a nice little plastic case.  The nice little plastic case will unfod into a three-way, self-standing little, well, stand.  You can carry it around, all nice and protected, then unfold it and stand it right up on the background, either vertically or horizontally. 
 

But here's the cool part.  They added a series of patches for making some basic, preset color corrections- warming, cooling, like that.  Almost like putting filters on the camera.  I feel like I'm writing ad copy here, but way to make a good product better!  Sweet!
 

Here's a nice blog entry on the XRite site showing all how to use it and all...  and a big shoutout to Jay Callum at EP Levines for the tip!