While on my bike I wave to anyone who looks.  Sort of like the "small town"
or "wide open spaces" type thing that someone from Louisiana mentioned. (Like
when I'm in Arkansas or Helena MT.)  Kids are especially fun - both genders
(Watch it Cliff!! :-) )  

In the cage I usually wave to bikers.  They usually don't wave back.  My wife
thinks it's strange but I don't care.