WP Minimize Admin Bar is a simple plugin that minimizes the WP Admin Bar (the bar at the top of the page that logged in users see). Instead of the typical WP Admin Bar that remains fixed at the top of the page, this plugin replaces it with a small, unobtrusive icon in the top left corner of your site. When the icon is clicked it reveals the full WP Admin Bar that you’re familiar with.
This plugin is available for download for your site.