chaimchaikin

Admin Menu Groups allows you to create nested menus in the WordPress admin sidebar navigation and organize all menu 
items in groups as needed.
A few notes about the sections above:
<ul>
<li>Create groups to organize the admin menu</li>
<li>Put less frequently used or advanced options in their own group</li>
<li>Hide unused items in the admin menu</li>
<li>Group related menu items</li>
</ul>

Admin Menu Groups

This is an underrated plugin. It is exactly what I expected: Keep my admin menu tidy since I see it almost everyday.

Especially impressive drag and drop tool. So I can make it works without finding any documentation like common plugins.

Thank you!

Underrated plugin

Admin Menu Groups allows you to create nested menus in the WordPress admin sidebar navigation and organize all menu items in groups as needed.

Maxaud

When creating a menu under the “Appearance -> Menus” tab it allows you to double click to expand and collapse a menu tree.
This is particularly useful for large menus or menus with many different sub trees that take up screen space.
Minimized menus will be saved as a cookie so when you return they should be minimized again.
Requirements
<ul>
<li>Javascript is required.</li>
<li>A browser that supports the :after CSS selector is required to show the minimized indicators (IE7 and IE8 may not show them).</li>
</ul>
Future releases:
<ul>
<li>Images to show collapsed menus rather than just a blue marker.</li>
<li>Double-click visual feedback.</li>
<li>your ideas!</li>
</ul>

Expandable Menus

Allows you to collapse and expand the WordPress admin theme menus (Appearance > Menus).

Admin Menu Groups vs Expandable Menus