How to complement eMail notifications with a notification bar? I am building a Drupal 7 website, and I noticed that you can install a facebook-like chat. This made me wonder if it is possible to implement something related to notifications that works something like Facebook. I simply want the notification "bar" to tell me if a user is posting a comment on my website, or if a new user has signed up. At this moment I just get an email about users trying to sign up.

I looked at the Notifications module for D7, but I am not sure this is what I am looking for. Or maybe I just don't know how to use it.
You may be looking for Heartbeat module:

Heartbeat displays user activity on a website. This module is an API to log activity. The logged data contains message structures, attributes and variables. Once the activity messages exist in the database, they will be parsed and build into activity streams.
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Heartbeat has global configuration for display, message template configuration and stream configuration.