You should see what turns up in the "free" category sometimes. Do a search on "Time Machine" and read this one guys ad. It's so obviously bogus it's a hoot!
And another theme that comes up sometimes: free dirt. The ads vary, but often I'll see in the body of the ad "free clean fill dirt, you load it, you haul it." and then they proceed to tell you where you'll be removing it from. Basically, if you read between the lines, they are saying "I want you to dig this hole for me, but I won't pay you to do it. You can keep the dirt though."