Kezz Bracey

This is a simple plugin that adds plugin & theme add & manage shortcut links to the admin bar for Multisite managers.
I’m constantly adding, removing and otherwise managing plugins and themes on my WP Multisite networks. I personally found it tiresome to click through to the plugin and theme management area of my network admin as often as I do, and wanted to speed up the process.
This plugin adds four links to the admin bar as a drop down, allowing 1 click access to add & manage network plugins & themes from anywhere in your network.
NOTE: Only super admins will see these shortcuts.

MU Admin Bar Shortcuts

This is a simple plugin that adds plugin & theme add & manage shortcut links to the admin bar for Multisite managers.

Geweb

Use this plugin if you want allow users create their own sites based on your.
<h3>Arbitrary section</h3>
You can create your own HTML code of the form. 
Create file in your theme, put code from plugins/wp-auto-mu/geweb-mu/register.php to your new file and add_filter geweb-mu-register-path to rewrite file paht for the form.

WPMU User own site

Plugin allows to create site on user registration in WPMU environment.

MU Admin Bar Shortcuts vs WPMU User own site