For my son's sixth birthday we had a party with a baseball theme.  The invitations were cutouts of hotdogs in buns that slipped into a wrapper. I purchased these at a card shop.  The food was stuff that you would find at a ballpark. We had hotdogs, nachos, peanuts, popcorn (I put this in popcorn bags I purchased at a paper goods store) and even cotton candy.  I used serving trays shaped like baseball mitts with baseballs in the middle for the food. I made both of the cakes.  One was a three dimensional baseball.  The other was a sheet cake decorated like a baseball diamond complete with players and candles shaped like baseball bats.  Of course the plates, napkins and cups coordinated. To keep with the theme I rented baseball highlight films to play while the party was going on.  The party was a HIT!!!