Craigslist has revolutionized the way people sell things to each other. Many believe Craigslist is one of the main reasons causing the downfall of newspapers because they used to make huge profits off of classified ads, not anymore.
Here is Craig's newest venture, which I feel is brilliant. I am more than cautious giving to charity organizations because a large portion of your donation goes to operating costs and not really helping the cause you care so much about. Here, you can forget the middle person and donate directly to somebody who needs it.
For example, you can do a search for any state, and say find a teacher who is looking to purchase material for class. You can donate directly to that teacher. Now, with anything somebody might try to take advantage of this so you always have to be carefull. But this is darn cool.