My kids play their Nintendo Wii pretty frequently and their friends sometimes come over after school to play the games with them. When we first got the kids the Nintendo Wii game, we just had the two standard controllers that came with the unit. We had to immediately get about two more wireless controller sticks because there were times when the whole family wanted to play a game. Then, when their friends started coming over after school to play, there was always a kid who didn't have a wireless controller and couldn't participate in the fun.
nintendo wii, wireless controller

I solved that problem by going online and ordering a pack of wireless controller units so that we would always have extra for anyone who wanted to play and to accommodate multiple players at a time. Of course, we were already the cool house with the Nintendo Wii game, but we quickly became the coolest house with the Nintendo Wii game because, as one kid put it, we had like a million wireless controller units! No, we really don't have a million but we certainly do have enough to keep a bunch of kids happy and not get bored.