A restaurant in Singapore is experimenting with drones to replace waiters...well...not entirely. They hope to be able to program the drones to take drinks and meals from the kitchen to a preset area in the room where a waiter can then take it to the customer. This was tried recently in the US but failed due to safety issues. Perhaps they are a bit more relaxed in Singapore.
The drones can apparently carry payloads of up to 2 kg. As a drone pilot myself, I really can't see this being a success. They fall out of the sky every day for a variety of reasons and are by default quite unreliable. They are also very noisy, can be a cutting hazard and generate a lot of turbulence. I guess time will tell on this one.