Wave, stop, circle the block, talk shop, drool over the nice ones, commiserate about damage, ask to crawl under to examine lifts, ask to sit in it to check out seats, talk about trails......
Its a more conservative wave than when I owned my YJ, those guys will high five each other at 35.
One other thing, I see a 4x broken down; EB, Jeep, Toyo, whatever, I stop to see if he/she needs help. It is something my first 'wheelin buddy taught me, and it has been a very satisfying habit. Doesn't take any skin of yer nose, and 9 times out of 10 they have it handled. I have had people offer me money for just stopping and having a hose clamp, or a 1/2" box end, or some duct tape. I won't take it. All I ever say is to stop for the next 'wheeler they see broken down. Well, I did take a beer once ;D I have heard the term "pay it forward", I always thought of it as just being neighborly. Our world needs more of it. Remember the "Good Samaratin's Clubs"? RV guys who stopped to help.
Hang in there, we're all in this together....
dpm