Download Link: One-Click Installer FireFox Extension.
Description: This extension can be used to install plugins or themes on your WordPress blog with a single click. It adds a new entry to the popup context menu for links to .zip files, clicking it installs the plugin or theme file on the Wordpress blog you have configured in the addons settings (the type – plugin/theme – is determined automatically).
Note: You need the following plugin installed on WP for this addon to work: Click Plugin Updater v. 2.2.