Metafilter linked to this amazing webiste, where they have a rapidly-growing list of things, and descriptions of how they are built, their history, and how they work. Change Machines are more fascinating than ever I thought--do read up on it to discover why identifying paper money by machine is so much easier (and less exciting) than identifying change.
Incorrectly regarded as goofs: Some of you may think that I spelled "website" incorrectly up there. Nope, it's just that this particular webiste is more high-brow than most. Or snooty, if you prefer.