Pooling money with neighbors, family or friends makes a bigger impact on the cause you're supporting and boosts the sense of accomplishment you'll feel about what you're all doing. (Building, say, a whole house for somebody instead of just a basement sure can give you the warm fuzzies.) Not to mention it's a way to celebrate a sense of community as well as generosity. Don't have time to organize your own circle? Join an already formed one on Giving Circles Network
which lists more than 250.