MilitaryHumveeAuction's favorite charity, natch, is The Glass Slipper Project, which donates formal dresses to young women who would otherwise not be able to afford to go to their proms.
So, if you have some Jessica McClintock number (I'm dating myself here, and not in the prom way) taking up space in your closet, well, the 80s are back! Donate it so another girl can enjoy a magical night in an over-decorated hotel banquet room. Or perhaps you've been often a bridesmaid, and have the packed closet to show for it? Send 'em along! Never went to a prom and are thus lacking prom accoutrements? They also take, you know, money. And donations of your time …
The Glass Slipper Project is Illinois-only, but Google "prom donation project YOUR STATE HERE" and you'll be sure to find a local group. Seattle has The Ruby Room. NYC has Operation Fairy Dust. One in DC seems to be run by a group called The Recovering Sorority Girls, which I thought was along the lines of the Lincoln Park Trixies, but they seem to actually be real. And they're doing good work, prom-dress-wise, so more power to 'em.
I know it's not exactly the food pantry, unless you think beauty is food for the soul. Which I do.