How to notify users of blog updates a la Admin Plugin Update notifications?

What I would like to do is mimic how WordPress shows an administrator how many new updates there are for installed plugins (a tiny number displayed next to a link). The main difference is that I want to serve this info to a logged-in user on the front end (since they last visited):

  • new messages they’ve received (Buddypress)
  • new forum posts (Buddypress)
  • new posts for “favorited” categories

Not sure where to find the code that provides plugin update notices but that would be a start…

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