http://us.cnn.com/2013/06/04/travel/...rticle_sidebar
What jumped out at me was this quote from George Hobica (founder of airfarewatchdog.com):
Hobica says that when he travels, he keeps valuables close at hand and avoids putting his luggage in the overhead bin.
"You can secure your bag under your seat with a cable -- that makes it harder to steal. It may sound extreme, but I don't think it's too extreme to guard yourself.
I do lock my bag(s) going through the checkpoint, and I lock any bag going in the overhead. I feel safer that way than cabling my unsecured bag to the seat. He doesn't mention what he does if he leaves his seat for any reason.
The only thing currently worth stealing from my 'seat' bag are my sound-isolating earphones, but I generally unplug the cable and leave them in if I leave my seat.