I usually try to avoid character type parties, but my son is actually partly named for Superman (his middle name is 'Steel' for 'The Man of Steel'), so a Superman party at some point was inevitable.
I actually found some cute store products, and filled in with some of my own stuff as well.
Cupcakes that were decorated with white chocolate Superman shields I made. The guests loved them & had to be convinced to eat the shields!
Activities / Games
I had capes for the kids and masks for the kids to decorate (with gems, puff paint, stickers, etc) and a homemade pinata filled with fun prizes.
When my son was presented with his cupcake that had a giant Superman shield & sparkler in the shape of a '4.' His eyes were so wide as he stared at his cupcake!
What People Ate
Pizza, salad, quiche (a request from the birthday boy) & mini muffins