Here's a website for great promise ideas. Check out We are What We do, a movement inspiring people to use their everyday actions to change the world. They've come up with 100 actions you can do to change the world. Here are my favourites:

Smile and smile back
Write to someone who inspired you
Do something you think you are unable to do
Don't judge someone by what job they do
Leave work on time at least once a week
Do something for nothing
Plant a tree
If it says 30mph, do 30 mph

Their movement is based on the belief that

small actions x lots of people = BIG CHANGE

They've also created 2 wonderful books that make excellent gifts.