Freeport and Walk the Plank fan Philip Minchin from Australia has written and packaged up a free PDF, "Reading the Skull and Crossbones." In it he presents a divination system from the City of Adventure, using the cards found in Walk the Plank.
And in case you haven't noticed, now is the perfect time to pick up both Pirate's Guide to Freeport and our family-friendly pirate card game Walk the Plank, since if you buy the book, you'll get the card game too, for free! (Offer good only in our Green Ronin Online Store, until such time as the boss tells the webmaster the deal is over. Free card game presented as option during checkout if the print version of Pirate's Guide to Freeport is present in cart.)
Also of note is our still-ongoing RPG Stimulus Package Sale, in which several Freeport books are still available at great prices.