When my kiddo was 9 we had a roller skating party for her. She loved planning birthday parties and we had really fun, elaborate ones. She seriously should be a party planner for a living. Anyway, we rented out the whole skating rink and since it was huge and it cost no extra to invite more, we invited everyone in both of the 3rd grade classes in her school.
But having just a plain old roller skating party wasn't that cool, so we made it a Roller Disco party and all the graphics were super great disco silhouettes, including her cake. Unfortunately the skating rink didn't really have a lot of disco songs to play...I really wanted Disco Duck which was such a fun novelty song they used to do at skating parties, and even if they hadn't heard it before I knew the kids would like it. But now we haz the YouTube.