Featured in a new book about the science of happier spending.

Happy Money by Elizabeth Dunn and Michael Norton

Here's an excerpt:

"Is it possible to let people taste the joy of making a positive impact for as little as a dollar? It's tough to imagine how such a small donation could make a difference - unless you join forces with others. In 2012, Daniel Hawkins formed the Dollar Collective. Members each contribute $1, and the group describes what random act of generosity to perform with the pool of money."