1. In a computing environment, a method performed at least in part on at least one computing device, the method comprising: determining, using a crawling mechanism, whether content associated with one or more external data sources has been previously presented at an interest group feed; on condition that the content has not been previously presented at the interest group feed, retrieving the content associated with the one or more external data sources; selecting, using a backfill mechanism, at least some of the retrieved content; associating the selected content with a permissioning scheme that controls access to the selected content, the permissioning scheme including one or more hierarchical permission levels; backfilling the interest group feed with at least some of the selected content in accordance with the permissioning scheme, the at least some of the selected content associated with a permission level that corresponds to the permission level associated with the interest group feed; receiving example content associated with a topic that does not correspond to an existing interest group feed; applying an entity extraction mechanism to identify seed entities related to the example content; generating a new interest group feed for the topic using the identified seed entities; and backfilling the new interest group feed with content identified based upon the identified seed entities.