aterris

Hidden Login provides easy and discrete access to the admin functionality of your site. Pressing the set keystroke combination will activate Hidden Login, either displaying a modal login window or redirected to the admin area if you are already logged in. Visit the Hidden Login Options to set what pages are enabled (All Pages or Homepage Only) and set your desired activation keystroke combination.
<h3>License</h3>
The Hidden Login plugin was developed by Andrew Terris, and is provided with out warranty under the GPLv2 License.
Copyright 2010 Andrew Terris (@aterris – andrewterris.com)
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

Hidden Login

Adds Keystroke Enabled Login Functionality

hauxh

This plugin allows you to require a secret key that is passed via the URL: http://example.com/post-title/?key=[string] 
Specify the key in a custom value called “key” with the [string] or use the built in widget.
Stable version of the plugin are pushed to the WordPress repository, 
but the latest version of the plugin can be found at: 
https://bitbucket.org/excion/wpkeyme/
Issues/Bugs: https://bitbucket.org/excion/wpkeyme/issues

WPKeyMe

This plugin allows you to require a secret key that is passed via the URL: http://example.com/post-title/?key=[string]

Hidden Login vs WPKeyMe