Hear ye, hear ye! Birthday invitations with old world charm are a great option for birthday kids who want to be swept back in time. If the guest of honor has a knack for drawing as well, maybe have him or her draw out a treasure map with the party location as the destination. Pick up some parchment paper at an office supply store, singe the edges with a match (parents only!) and crumple it up to form some time-induced wrinkles in the paper.
Bonus points for using Old English fonts and applying a gold seal to envelopes before handing out the invitations!
Complementary Party Themes: pirates, shipwreck, princess, knights.