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Spark Fun has the new Blueye Bluetooth MP3 cellular bridge with moddable firmware - "The Blueye from Mavizen connects via a wired connection to any MP3 player with a 3.5mm audio jack. The Blueye then wirelessly connects to your Bluetooth enabled cell phone. When an incoming call is detected, the music is muted and a ring tone is heard (yep - you can even record your own!). To answer the call, you can either press a button on the Blueye or by voice activation. Cell phone stays in your pocket, your favorite MP3 ear buds stay in your ears. Keep on running, driving, or soldering, without missing a beat. Another highly refined retail product hits the market, and they've even opened up the code for customization! Customers can roll their own firmware by accessing the Blueye documentation Wiki..." - Link.