Dumpster diving is intimidating for many (not to mention illegal). Freecycle is great, but old magazines or tin can lids don't seem worthy of mass emailing.
Many cities have specific locations (often next to/part of recycling drop-offs) for sharing free stuff.
The puruser still finds treasure at her own risk, but doesn't have to sort through rotting veggies to find wood scraps for a home improvement project.
Bins can be labeled clearly to make organization easy.
Perhaps the recycling center has some space to share? If not, maybe some abandoned building could be put to use?