Module Development
Use Group Purl on your Group site!
One big missing part of the Group module is setting up friendly URLs that contain the group in the path for group content. You can't set this up in Pathauto -- the tokens are too limited to handle this correctly.
Ask Freelock: ECA vs Rules
Yesterday a client asked us to install Rules module (again, repeating an earlier request, when he had missed my answer that we had installed ECA instead).
Aggregate fields in Drupal 8 views
Views module has long been the killer feature of Drupal, making it easy for a site builder or skilled administrator to essentially create complex SQL queries through a web interface, without knowing SQL.
Getting the group into the URL with Purl
The corners of Drupal 8 that aren't there are quickly dwindling, but there are still some that need to get worked out. While upgrading our internal issue tracker, we hit a new one -- getting a group context set via a URL alias, and generally keeping posts within a group.