I'm sure full historical accuracy goes against canon for PotC ;) But I'm signing up anyway because accurate historical detail is one of my favourite things, even if all I do is take liberties with it.
The Salacious Historian's Lair is a wonderful site with Pirate resources coming out of its ears. If you want to know the price of a cask of good rum (or poor rum) in 18th Century pounds or modern dollars, or the typical travel time from Boston to Barbados, this is the place to look.