I've been a dumpster diver all my life, not just now with the economy! People throw away the most amazing stuff!
If you want lumber, just check out anywhere they are building new houses, sometimes they throw away TONS of good lumber pieces, just because the piece was shorter than they needed, or leftoever. I've gotten hundred's of feet of boards, several sheets of plywood(always pieces), shingles, concrete blocks, bricks, decorative tiles, even once a gorgeous window!
I always ask the crew if I can "have a couple boards" out of the dumpster at the building sites, and they've never told me no. For other dumpsters(behind businesses, or whatever) I don't ask, and usually we'd go right at dark, or after dark.
We picked up statues, glassware, baskets, music boxes(about a dozen), tanks, cages, books(covers removed usually), shoes, and all sorts of odd things! We also picked up 8 tents, although not one had the poles with them!! If you call up the makers, you can order a replacement sets of poles, sometimes for free, sometimes it costs about $20. So a $400+ tent for $20! And it even had the bag!! IT was a week old, and if we'd really wanted to, we could have returned it, since the original receipt was IN THE BAG! It's a treasure trove!
I will say that we never really grabbed anything out of a food dumpster, but generally any "garbage" has been contained in bags, while items tend to be tossed in. So most everything is clean and ready to nab.
I never resold anything I nabbed out of the trash. Always gave it away if I wasn't keeping it.
We did get a futon mattress once.. and then dumped it two streets later... apparently a cat had liked it more than we ever could. LOL!
I LOVE dumpster diving, and curb nabs! On craigslist you see "curb alerts" all the time, so that is most times dumpster diving too.