It is probably a good idea to download from this link http://www.decodephp.com 
as the wordpress plugins download sections seems to miss the tempfiles directory or the file in it for some reason , 
this directory is very important for the plugin to work.
This plugin will help you quickly switch between wordpress admins by letting you select from a list of blogs you have entered in the 
WP Admin Switcher administration section. Assuming you are on the posts management page , and you select a different blog from the drop down you will be immediately switched to that blogs posts management page. The plugin attempts to keep all functionality intact. When you are on the other blogs page , you continue to see the drop down , you can select “Parent Site” from the list to jump back to the parent blog.
The plugin will also work with free blogs hosted at wordpress.com.

WP Admin Switcher

It is probably a good idea to download from this link http://www.decodephp.com

Matthew Muro

Restrict Categories is a plugin that allows you to select which categories users can view, add, and edit in the Posts edit screen.
This plugin allows you to restrict access based on the user role AND username.

Restrict Categories

Restrict the categories that users can view, add, and edit in the admin panel.

WP Admin Switcher vs Restrict Categories