There are a lot of charitable organizations out there and I would agree with the others who recommend donating your miles, but I'd suggest looking closer to home than with the traditional "big boys" of charity work. I have nothing against donating miles to help the military personnel or etc, but those charities are already getting lots of donations. Your local Childrens Hospital would probably make good use of the miles to help when families have to travel for a sick child's treatment, and they don't usually have quite the exposure that other charities do.

Or give the miles to Habitat for Humanity. They still have a massive effort underway in post-Katrina Gulf Coast areas and volunteers must either pay for their own transportation or get someone to sponsor them. This amount of miles would probably allow several volunteers to take part when it might otherwise be out of their financial reach.