According to Wikipedia, Cinco de Mayo is more heavily celebrated in American than it is in Mexico. A common misconception is that Cinco de Mayo is Mexico's Independence Day.
Does anyone do anything special for the 5th of May yearly? I actually have friends who take off the day after Cinco de Mayo in anticipation for a hangover! While I'm happy to use any excuse to go out to drink beers, I seldom if ever have done anything to "celebrate" this informal holiday.