How about walking around as a kid with the postman on his route (well, the couple of blocks near your house) or even, now-a-days, actually knowing your post-person.
Also, I do remember milk delivery, but seem to recall seeing the Diaper Service as well. And visits from the Fuller Brush Man.
Also, folks from the neighborhood coming around and collecting for charity. You would sign up and get a block or 2 to collect from, I forget the charity.
And, lest we forget, S&H Green Stamps. And some other brand, I forget, they weren't green.