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.

Mehdi Kabab

When your permalink structure does not end by a trailing slash (/), all your links look like http://example.com/2009/05. Permalink Trailing Slash Fixer add the missing trailing slash.
<h4>Example</h4>
If you have a site with the following permalink structure <code>/%category%/%postname%.html</code> and your permalinks 
look like these:
<ol>
<li>Single Post: <code>http://example.com/my-category/sample-post.html</code>.</li>
<li>Category: <code>http://example.com/my-category</code>.</li>
<li>Archive: <code>http://example.com/2009/05</code>.</li>
<li>Page: <code>http://example.com/about</code>.</li>
</ol>
After activation of the plugin:
<ol>
<li>Single Post: not modified.</li>
<li>Category: <code>http://example.com/my-category/</code>.</li>
<li>Archive: <code>http://example.com/2009/05/</code>.</li>
<li>Page: <code>http://example.com/about/</code>.</li>
</ol>

Permalink Trailing Slash Fixer

Quickly add a trailing slash in the URLs if it's missing in the permalink structure.

Simple Import Users vs Permalink Trailing Slash Fixer