This is, by far, one of my favorite challenges! Locks of Love is a non-profit organization that provides hair pieces to disadvantaged children under 21 that suffer from any diagnosis that causes hair loss. One of my favorite parts of this organization is a part of their mission statement:
I actually did this in 2009 and just yesterday my hair was long enough again, so I cut it for a second time! Once they use your hair, they mail you a card saying thank you. It's a great feeling :)
On a side note, don't forget tomorrow is Martin Luther King Day of Giving Back! Many towns hold fundraisers or other charity related events, so check them out!