5. Smart light bulb
What about a regular light bulb? Does it need to be smarter than it usually is? It appears smart light bulbs are very convenient. You can switch them on/off or change their brightness remotely.
And, besides, there are light bulbs like Philips’ Hue lights, which are color-changing and can be synced up with apps on your mobile. For example, they may flash when you receive a message. Or you can connect a couple of light bulbs to a musical app to arrange a light show.