I have several pirate things that may work for your party. First, I made two images for you that you can use lots of ways. They are 8x8 inches but you can resize them to 2x2 to 2.5x2.5 inches to use as cupcake toppers. You can use them at the full size as decorations to hang from a chandelier or around the room or even on the front door. You can also use them with a fun pirate paper as napkin rings.
Here they are...if you like them please don't quote them and make sure you save the images so I can delete them to make room in my photobucket:
The ship appears a little bit fuzzy in these images, but I made it extremely large so you could play with different sizes. It should be fine if you use it for images 8x8 inches and smaller.
In addition to these images, I have POTC candy bar wrappers, bag toppers and invitations in my 4shared file in the "blank invitation" and "candy wrapper" files.
Finally, I have a pirate certifacte that the "pirates" at your party can sign and take home along with Pirate ID's that they can carry around. They probably won't work for 3 year olds but if you have any older kids (5+) they will love them. You can find them in the "drivers license-certificate" file in my 4shared things.
That should get you started.