Friendship Lamps
Each set has a specific group identity and you use that to connect to as many as you want. And the app that you use is super user-friendly.
Once they are connected, everyone picks their own color for when they touch their lamp. Then when someone touches their lamp, everybody's lamp lights up in the color of the person who touched it.
There's a whole rainbow of colors you can choose from, which I love, so everybody has a different color. We got them for a community of about 30 people and they're all connected with their own unique colors.
I also bought these for my family so I have one at home and one in my office.