This module provides a toolbar at the bottom of the window, like Facebook's Application Bar, which can hold blocks and can provide real-time alerts about activity on the site.
The module is highly extensible. Drop-in styles are supported, and the module comes with three styles by default.
Appbar integrates with Views, Activity, Rules, and the core Trigger module. This combination allows recording actions for a wide variety of modules. Rules is currently recommended to set alerts in the 2.x branch, although future development will probably switch to primarily using Activity.
This module is in a period of rapid development. The module is currently working and should be reasonably stable in the sense that it won't break your site and there probably aren't major bugs, although there may be scaling issues. However, things are changing quickly. Do not use this module on production sites without testing.
The 2.x branch currently requires that administrators create Rules (preferred) or Triggers to set alerts for the appbar. The 1.x branch comes with some alerts by default, but it does not support using blocks. Later iterations of the 2.x branch will probably use Activity as the alert system instead of Rules. No new development will occur on the 1.x branch, so I strongly recommend using 2.x.
The following features may or may not be developed:
* Add the ability to minimize/collapse the Appbar, potentially with the ability to remember the (un)collapsed state via session or cookie
* Allow individual users to disable certain kinds of alerts
Appbar 6.x-2.0 will be released when these features are implemented and I consider the module stable enough.