Well, I was never a big one for "celebrating" this day - I'm not really a prankster by nature, and I can't remember a time when someone really got me.
Still, in honor of this day, you might be interested in reading the History of April Fool's Day.
If you're feeling smart, take this April Fool's Day Quiz.
And here's an interesting site to peruse: The Top 100 April Fool's Day Hoaxes of All Time.
Finally, here's a good April Fool's gag on Hollywood Squares host Tom Bergeron: