All contributors to Easy Beer Money optionally tithe themselves by donating 10% of their beer money income to a charity of their choice.
One site used for such donations is Karma Karma. Karma Karma uses a point system, with various social impacts costs a certain amount of points. 1000 points costs $1.00 (unless you buy in bulk or get the points from e.g. Swagbucks) which, as you would imagine, fund more social action in the developing world than in the developed.
The social impacts on Karma Karma are divided into six categories: animals, the environment, human health care, humanitarian aid, education, and human and social support. The site incentivizes “spreading the wealth” in two ways: by giving you incremental goals, and tracking your progress in ways that highlight which categories need your attention more than others, and how much of the World your giving is touching.
There is also a map with pointers to where current projects in need are. This map further incentivizes wide engagement, since when you do an impact, a grey marker is filled in with a color (depending on the category to which the action belongs) indicating completion of a task.