The history of currency, for some, is seriously tantalizing stuff, for most others, perhaps, not so much. There are a few notes of US currency, however, that have always seemed to elicit a sort of underground interest among folks, most popular among them being the US Two-Dollar Bill. Lots of people seem to share an interest and general affinity toward this US currency note and, quite interestingly, perhaps even more people than that literally do not even know that they exist!