My son turned 2 and we had a "Sports Balls" theme because he absolutely loves balls of any size or type. I made the invitations on the computer to resemble a ticket to a sporting event and I inserted a picture of my son in the middle.  The invitations were very easy to make and I received a ton of compliments.  We had the party in our backyard and had a total of 29 people (6 kids and 23 adults). The kids ages ranged from 2 – 7 years old. For decorations I bought sports related plates, napkins, tablecloths and centerpieces.  But I also made some pennants from large pieces of stiff felt and also printed off pictures of sports balls on the computer.  In the yard we had a small basketball goal, inflatable football goal (that I ordered from Oriental Trading Company) and a swimming pool full balls (similar to the balls the kids jump in at Family Fun Centers). One game was a competition to see who could throw an inflatable football through the football goal the longest distance.  This game was great because even my two-year old son could play. All the kids received a prize for this game and it was a gold medal (the medals were only $3.50 for 24 at Wal-Mart).  And the kids loved wearing their medals the rest of the day.  We also had a baseball shaped piñata. The piñata was the traditional piñata that you hit with a stick and I was a little worried to give toddlers a bat. I found a foam padded stickball bat at Wal-Mart for only $3 and it worked out great. The bat was really light and even the little kids would take a swing at the piñata. The kids loved hitting the piñata and were still talking about it at the end of the day.  Our last activity was to make a sports magnet. I ordered the pre-assembled kits from Oriental Trading Company and they were very inexpensive.  The kids really liked making the magnets. I recruited some of the other parents to provide assistance for the assembly of the magnets. The 5-7 year old kids really loved this project and each of them made more than one magnet.  We had two cakes. I made a football shaped cake. Bake one cake mix in an 8" circle pan and an 8" square pan.  Flip the circle cake onto a tray and cut the square pan diagonally and put one piece on each side of the circle and the shape will resemble a football.  I found the recipe on Pillsbury.com.  The other cake was a cupcake cake in the shape of a basketball.  I ordered it from Wal-Mart for only $11.88.  It was 24 cupcakes put together in a circle with orange icing and it looked exactly like a basketball.  The kids loved the cupcakes.  For goodie bags I bought brown paper bags and stamped the outside with sports balls.  I filled them with jet balls, bouncy balls and little bendable sports guys. For the adults thank-you gifts I bought Baby Ruth candy bars and printed labels on my computer that read "Thank you. It was a Grand Slam!"  I put the labels on the candy bars and handed them out as the adults were leaving.  I'm pretty sure all the adults and kids had a good time, but the best compliment came when my seven-year old nephew left and told me "this was the best party ever!"  I hope some of these ideas help you plan your sports theme party.