Great Game Ideas!
A fun game is called Bigger or Better. You start off with something small like a soda can or even a paper clip.
You go door to door telling them that you are on a scavenger hunt for a birthday party and ask if they can trade you any object that is bigger and/or better than this.
We've ended up with a dvd player (broken) and a painting that we were told would be worth hundreds in a couple years.
You can either give a time limit or you can give a certain number of houses. Make sure to give everyone a chance to ask! And go during the time of day when most people will be home.
I don't suggest going later because people might be putting their kids down and they tend to be more agitated and less giving.