To wave or not to wave

After seeing the video for things cyclists say, I found this blog entry from peopleforbikes.org. For the record, I am a big proponent of waving/belling/saying Hi to everyone; cyclists, pedestrians, cars, etc. And it's a nice acknowledgement that facial expressions can influence your mood. Read the entire piece here.
To wave or not to wave: is it even a question?
Posted on Dec 1, 2011
One morning earlier this fall, our president, Tim Blumenthal, arrived at the People for Bikes office with a new resolution. "I vow to say 'hi' to every other bike rider I pass on my way to work," Tim declared. "Every bike ride should be a celebration. I'm happy when I'm riding my bike. At the very least, I should muster a smile for the fellow riders I encounter. There's no room for being smug."
This idea of Tim's got the rest of us thinking. Why should we acknowledge other bicyclists, and how should we do it? And what would it look like if every rider did this?
It's safe to say that greeting another cyclist-whether it's with a nod, a smile, a wave, a bell ding, or even a "hello"-can't hurt, perhaps except in special situations. If you're flying down a winding, technical descent, you might not want to remove your attention from the road right in front of you. But in most cases, a simple greeting will do no harm. Smiling at another rider will probably make both of you feel good. Research shows that your facial expressions can influence your mood.