Let's see, U groove, Splitfire, E3 and a bunch of others. They are all gimmicks. If you run a standard plug with the correct heat range and keep the electrodes filed flat and properly gapped will perform as good as it gets. The snake oil marketing wanks hawk their BS with the usual lack of any real engineering.
Many avaition plugs have multiple ground electrodes but that is for redundancy not performance. Same for some marine plugs.
It is amazing how many companies since the invention of the car have made magic products you can pour into your gas tank or oil pan or bolt on to fix anything, maybe even cancer. Magnets on fuel lines, super spark plugs, ionizing fuel pellets, directional plug wires, gap boosters, etc. Too bad all of those engineers who actually design equipment don't know about these miraculous products.