Boone Gorges

Requires WordPress 3.0+ Network Mode.
Allows blog administrators to add multiple users to blogs at a time, using only a list of email addresses. When the specified email address matches an existing account, the account will be added as a user on the blog. Otherwise a new account is created and the new user added with the specified role. Based on DDImportUsers.
The plugin determines username automatically from the email address. For example, the email address bgorges100@example.com will produce the email address bgorges100. For that reason, this plugin works best when used in schools or organizations with official, unique email addresses.
When BuddyPress is installed, the welcome email will also include a link to the new user’s Edit Profile screen.
This plugin was developed for Blogs@Baruch of Baruch College’s Bernard L Schwartz Communication Institute. http://blsciblogs.baruch.cuny.edu

Simple Import Users

Allows blog administrators to add multiple users to blogs at a time.

Victor Barkalov

This plugin allows you to add custom links and menus to the toolbar in the WordPress admin dashboard. By adding custom links, you can make the WordPress administrative section into the center of your admin universe. A typical use case would involve adding the link to your web host’s CPanel.

Custom Links On Admin Dashboard Toolbar

This plugin allows you to add custom links and menus to the WordPress admin dashboard.

Simple Import Users vs Custom Links On Admin Dashboard Toolbar