I believe that having something new on the homepage when returning visitors arrive will make them come back more often.
To accomplish that we have a script that rotates content through a few of the blocks on our homepage. The script runs every hour so if a person returns later in the day they will see different items. We have enough content in this rotation that the typical visitor could make many visits before seeing the same item a second time.
Also, on most pages of our site we have links to our ten most recent blog posts that match the category of the page. These update every hour as we make up to ten blog posts per day. We also have lists of "related articles" that rotate hourly.
All of this keeps almost every page of our site constantly changing. I don't know what google thinks of it but adding these rotating content features has increased the visitor engagement level of our site.