A tip jar system comprises a receptacle for receiving a deposit of money and a signaling apparatus for sensing the presence of a person depositing the money in the receptacle and for responding to the sensed presence. The signal provided is generally of an amusing sort and preferably provides both audible...http://www.google.de/patents/US7378981?utm_source=gb-gplus-sharePatent US7378981 - Tip jar providing audible and visible signals
