Google classroom is an incredible resources for teachers in their classroom, but it also a great resource for administrators and professional learning. Using Google Classroom, teachers can upload videos and be assigned videos to watch. This allows for online learning for teachers with assignments and lesson study they could complete at their own pace and without the need of hiring subs to help for observations. I learned about this at a conference I went to, and I thought it was an innovative way to allow teachers autonomy in their learning, but still provide accountability. I think this would also work really well alongside what Zach wrote in "Flip PD with Videos"
Google Classroom allows for tracking of assignments and work, so it provides accountability for completing lessons and gives a chance to set goals and deadlines. This makes it a great platform for guiding a series of professional learning.
I think this could be implemented by starting with teachers setting individual professional learning goals. Then teachers can post videos and provide feedback to one another using the other google tools. This could be peer-to-peer work, or could be facilitated by administrators.