Fark today points out
this story of a Mexican drug raid, centered around trackers in pseudoephedrin -- you knew it as Sudafed, and it's used in making methamphetamine.
Before Sudafed (and other such medicatinons) changed the formula (to something less effective), meth lab people were buying and stealing it in large quantities. When the US cracked down on it, Mexico became the largest producer of it - and thus, the Mexican traffickers of it got rich beyond belief.
Thus, most of the bills there are 100s. From a decongestant that was sold over-the-counter a year ago.
More pics are at the slideshow linked from the story.