I just worked with a client where a few specific groups had content calendars as the group was getting up and running. But it was less at the network level and more business focused around the group. Ideally it was the content that was normally in a content newsletter. Like Product Updates, Org Changes, Industry news/updates, etc
I really liked ending the week with Highs/Lows as a team - again at a group level not at a network level.
More at the network level we would do "What you may have missed" a few times a month. I've heard a few groups doing #throwbackThursdays - or something like Remember when... or pictures from the early days of the company, or #thankfulThursdays where people encouarge others to recognize eachother weekly.