Gosh darn it! I missed Mole Day yesterday!
What's Mole Day? It's not a day celebrating the burrowing mammal. Instead, if you remember your high school chemistry, it's a day that celebrates Avogadro's Number (approximately 6.022×1023). That's Mr. Avogadro on the left there.
Chemists in US celebrate Mole Day between 6:02 AM and 6:02 PM on 10/23 (6:02 10/23 - get it?).
Link - Thanks Andrew Lawandus!