There's an article here on the history of the day, and what folks are doing to celebrate.
And I've decided it's 'Fic Like a Pirate Day' too! If you've written Pirate fic, or would like to rec some, let me know about it!
I've got but two stories featuring the bonnie Captain Sparrow: Now We Are Met Again & One Day
And ninjababe has a nifty little fic about the first time Jack met Methos, titled 'Drink Up'
A bit later: Very funny little fic here where Jack and Barbossa discuss the proper way to talk like a pirate.
More later: Another short fic I enjoyed -- Lessons