Halloween candy works beautifully for decorating gingerbread houses. Tootsie rolls make nice logs for a wood pile. Dum Dums make great light posts. M&Ms, Smarties, Skittles, etc make great shingles and "lights". Of course then you have to keep the kids from eating the decorated house, but that seems to be a lot easier than stopping the plundering of the pumpkin. So we eat a little of the good stuff - chocolate - and save the rest to decorate houses.
I love this idea!! Luckily the candy hasn't been an issue here, it's been largely forgotten about (except by me), but I will definitely save it for gingerbread houses instead of ditching it. I think I have some old pinata candy, too.