I asked if we could get a video of the gear warning system from aircraft incorporated that uses the transducer. I was sent this, pretty neat, not sure if the transducer would ever have any trouble under certain types of terrain but overall seems to be a pretty interesting system. Other option I could see would be a GPS AGL warning from foreflight or something similar as carusoam mentioned
I wonder how well these gear warning systems work. This P/N 2037 from Ohio has a ground sensing transducer of some sort detecting 100-150 AGL and has a voice audio alert http://www.flyingsafer.com/p-n-2037.html I've also read of the P2 audio system based on airspeed http://www.p2inc.com/techsupport.asp I think it's something to consider, if it would give some peace of mind.