Our cake - we got lots of madeira cakes, sandwiched them together with jam and matchmakers to brace, then shaped into ship shape - so pointy bow, squarer stern, raised deck at stern. Used chocolate butter cream icing to cover. Barbecue skewers for masts, rolled out marzipan for sails, writing icing pens for detail, curly wurlys for rails/rigging.
One idea which a friend used and I WISH we had thought of was to use one of those long biscuit tube things - the sort that is a sheet of biscuit rolled into a tube - get them in posh belgian chocolate selections - for the prow at the front. She then made an icing figure head, but we didn't bother with that.
Games - we had the treasure maps to make (get pieces of paper, rip the edges off, scrumple, soak in strong cold tea for an hour, leave to dry (this takes a while - we left them overnight, then finished them in the oven) - I just put the blank parchments on a table, with a prototype stuck to the table and lots of crayons, and it was a good 'quiet' area.
Bouncy Castle - was Pirates of the Caribbean.
Games - Sleeping Pirate - children sit in a circle, one child in the middle, put a big bunch of keys beside them, they are blindfolded, you tap a child on the head, they sneak up and take the keys, then pirate has to identify who has the keys - they get 3 guesses. This worked REALLY well.