I have been using a Macbeth Color Checker Chart for quite a while now and just recently stumbled across there new Passport system. It is actually a series of Charts and Cards combined with a software system for your computer that works directly with Photoshop to produce a calibration for a batch of images. I have been very satisfied with the results of the Color Checker and would love to fiddle around with the new system. For now, check out this video from X-Rite.