When in my Wrangler, I wave to EVERY Wrangler and modified Jeep. I even had a guy in a jacked Land Rover wave to me (first) which I thought was cool. When in my WJ, I occasionally will give or get a wave from another Jeep. I live in CT where wheeling is almost non-existant and every f-ing soccer mom has a 4 door. I wave especially obnoxious to those people...hand and arm out the window waving like a lunatic.
You could always do one of these: jeepwaves.com - Home of the Jeep Wave Sticker
It is a simple sticker that goes on your drivers mirror.
I think you have to keep the "club" alive...F the ones that don't participate. It should be something that is told to you at the stealership before you even buy a Wrangler. It should be on page one of the owners manual or stamped on your visor!!!!