As I scrounged around to look for a zany holiday to discuss today, all I could ultimately come up with was this little gem of historical significance--the anniversary of the chartering of the USA's first national bank.
Tired of using change purses to hold their considerable wealth, early Americans chartered the First Bank of the US in Philadelphia. Slated as a national bank by Mr. Alexander Hamilton himself, the institution unfortunately lost its charter in 1811. People made a second vain attempt at a national bank shortly thereafter, but that was messed up too. Since then, the country hasn't had a central bank at all, opting instead to dump the resposnsibility on the Federal Reserve System.
I'm not sure how you'd celebrate today, um, buy a bank cake? Make a deposit? Do a little dance while waiting in line at a bank? Just be creative or something.