For a group of teachers working in language arts classrooms, common shared resources might include sites connected to reading, writing, problem solution essays, evaluation essays and poetry resources. For social studies teachers, shared resources might include sites connected to topics of study like Greece, Rome, World Wars, Middle Ages, Europe, South America and current events.
Common tags, then, could include the name of their school, followed by their grade level, content area, and topic of study. Here's an example of the tagging language that my professional learning community has developed:
salem6la_reading
salem6la_writing
salem6la_ps
salem6la_eval
salem6la_poetry
salem6ss_rome
salem6ss_greece
salem6ss_ce