Although Pantene's wigs go to cancer patients, there are several groups that accept donations and give wigs to children facing hair loss for various medical reasons, (such as alopecia areata, an autoimmune disorder that destroys follicles and results in hair loss), and other selected groups (many of which require 10 inches, so make sure you don't cut too soon if you are donating to one of those!). I have heard that Beautiful Lengths is one of the more trustworthy ones, and that some other charities sell a lot of the hair received to commercial wig-makers, so make sure and do your research before donating. Here's an article that lists some different charities.
I first learned about the hair-donation idea from midnight7, who did it back in college and donated a lovely looong ponytail at one point. :) She looked adorable with her newly short cut after the donation, and I'm really, really enjoying my short cut, so that's an added bonus to the nice feeling of trying to help out in some way. (Dave likes my new cut, too. ;) Sadly, I am sure we all know someone who's been diagnosed with cancer, and I know at least one person who has alopecia, so by donating, you may even be helping someone you know; or someone who's experiencing the same condition. So...grow that hair!