Web site Cool Tools recommends the Lee Valley Jar Opener, an unassuming piece of strategically shaped metal that takes all the work out of wrestling a jar open:
You simply place it on the top of the jar with either of the rolled sides caught just under the edge of the lid. Your fingers hold the piece in place, which acts as a lever, and the bend in the metal serves as the fulcrum. The downward pressure of the heel of your hand provides just enough force to release the vacuum without distorting the lid. I can happily report no more bent spoon handles, no more splatters, no more spills, just a nice "pop" sound when the vacuum has been broken.
This looks like a more effective alternative to my current jar-opening weapon, the circular piece of grippy rubber. The Lee Valley Jar Opener will set you back $US8.