Yesterday, on the way home from work, a car hung well back behind me for quite a while before the road widened sufficiently for them to pass me safely. I did give them a little wave of thanks but I guess they probably just wondered who they hell I was. 
This morning I passed the karma on.
I was in a bus lane approaching lights. A car in the regular lane was indicating a right turn into a side street so I held back and when the lights changed I waited a moment to let him turn in front of me. That driver did give me a wave.
And hopefully he did something courteous to someone else down the road (maybe another cyclist?)

This morning I passed the karma on.
I was in a bus lane approaching lights. A car in the regular lane was indicating a right turn into a side street so I held back and when the lights changed I waited a moment to let him turn in front of me. That driver did give me a wave.
And hopefully he did something courteous to someone else down the road (maybe another cyclist?)