Three or Four times a day, I say hi to someone I'm next to, using their name, and they don't even acknowledge it. I wave to people walking at me, nothing. And of course, the worst, I walk behind people who take up the whole hallway and are oblivious of people who want to pass them!
I'm asking you, pleaes be aware of your surroundings, when walking, when driving, when riding a bike, or just sitting down. Wave back to people who wave at you. It makes the world a happier place. :)