Check around and see who in the area is interested. This is what it could include: if you are going grocery shopping ask the neighbor if they need a few things. If you are picking up takeout see if the neighbor wants something. If a neighbor is going out of town, pop in and feed the pet. Swap magazines and rented videos. And I am sure we could all think up more!
Saving the sunday newspaper and monthly magazines to swap is a great idea for neighbors- especially the elderly on a fixed income. I save all my monthly magazines and my 96 year old mother in law and her friends pass them around to read. The elderly are often lonely and bored and this gives them reading material they sometimes can't afford to buy on their own.