I don't know about you, but I just don't fly enough to ever make my airline miles count. And instead of letting them disappear every 18 months, I donate them to worthy causes like the Make a Wish Foundation, Hero Miles, and St. Jude Children's Research Hospital.
If you have unused airline miles, donating them is such a great way to give back.
Delta makes it easy to donate to over a dozen charities. Donate Delta miles
American Airlines has a couple of charities to donate to on thier website. Donate AA miles
Donate Miles to the Make a Wish Foundation
Donate Miles to Hero Miles for wounded, injured, and ill military members and their families
If I didn't list you preferred airline or charity here, visit their website and search “donate airline miles”.