So imagine you are walking down the streets of Pittsburgh, it is pouring rain, you are about to become soaking wet... when some kind stranger hands you an umbrella. A random act of kindness... yes, but there is one string attached. The umbrella comes with a note that says you are now responsible for paying forward an additional act of kindness. When you are done, you are instructed to share your story via a prepaid postcard. You can read all the postcards on the Here You Go blog.
My favorite part of this is that most of the postcards are all wet, as if people were inspired to go out and do their good deeds immediately.