How to customize the admin toolbar in Drupal 7? I'm trying to customize the administration toolbar in Drupal 7 but I don't know how to do it.
I'd like to add custom links (e.g node/add/[content-type]) and links that are only available for specific users. 

[Edit] Finally, I used admin_menu module and I added a menu item with a custom module using hook_admin_menu_output_alter
Take a look at the Quickbar module.This is a simple administration toolbar. It allows you to take any menu and assign it to a role. This menu will be displayed at the top of your page as an administration toolbar.

You could also look at the Manager module. It includes the Manager's Bar. An admin-bar designed for users that aren't familiar with Drupal. It is like the default "Navigation" menu, when we cut off everything that doesn't matter to this users, and it looks like some known admin-bar-modules, like Admin Menu, but a lot more simple.