A beeping noise, with long pauses in between beeps at first, then shorter and shorter until a continuous beep. . . Could be used like a timebomb i guess.
Sounds of an ordinary kettle being used in a manner similar to a water gong: struck and then the sound of the resulting clang being modulated by the moving water inside.
Using an atm kiosk: sounds of pressing chunky metal buttons and the resulting beeps, as well as the motor of the atm as it ejects money and prints a receipt.