There's always $e$ day, which falls on the 72nd day of February (rounding 71.8 up). Note that which day in the usual calendar this is depends on whether it is a leap year.
In Europe, and actually everywhere that is not the US or Liberia, they celebrate $e$ day on the 27th day of Hexadecember (the 18th month), just like $\pi$ day in the rest of the world is on the 3rd of Dodecemeber.
