SNIFFING AND DECODING BLUETOOTH LE ADVERTISING PACKETS AND NRF24L01+ COMMS. FOR UNDER $30
http://hackaday.com/2014/01/22/sniffing-and-decoding-bluetooth-le-advertising-packets-and-nrf24l01-comms-for-under-30/

REVERSE ENGINEERING BLUETOOTH USING ANDROID AND SPOT AS AN EXAMPLE
http://hackaday.com/2011/12/05/reverse-engineering-bluetooth-using-android-and-spot-as-an-example/