Here is a small idea, which can be put into practice by Telecomunication Students..
The Problem : Many time when we go to small/medium restaurants, you must have noticed, we have to call waiter, many time...he may not be around and we get irritated.
The solution : Develop a device, wrist watch type, where there will be numbers. When a guest press a button on the table. the table No, will display with sound alert.(the wrist watch type device must be on the waiter's wrist) the alert will go on as long as he come back and press the button on the table. Enable it in such a way that the wrist device and button on table are close and press the table button then only the alert sound will stop.