H. Peter Pfeufer

Provides a setting to show or hide the new admin bar in WordPress 3.1

Show/Hide Adminbar in WordPress 3.1

Provides a setting to show or hide the new admin bar in Wordpress 3.1

Marcel Bootsman

Auto Hide Admin Bar makes the WordPress Toolbar disappear – and reappear when hovering the mouse pointer over the top of the browser window. 
You end up with a clean view of your site, and keep having access to the WordPress Toolbar. 
If you have any comments or questions, please use the <a href="https://wordpress.org/support/plugin/auto-hide-admin-bar" rel="ugc">support forum</a>.

Auto Hide Admin Bar

This plugin adds an auto-hide feature to the WordPress Admin Bar or Toolbar.

Show/Hide Adminbar in WordPress 3.1 vs Auto Hide Admin Bar