Cell Phones on Airplanes?! Jam!

In some nations around the globe, cell phone usage on a plane is okay. Geez! You are jammed into a coach seat with no legroom - and now I have to listen to the guy/gal to my left and right yap away on their cell phone too? I'll be looking to buy one of these, for just $50 - a cell jammer! Illegal in some places probably, but what about my peace of mind?