OzTheGreat

For WordPress Multisite (WPMU) installs, allows Super Admins to easily manage each users roles and blogs from one 
screen in the Network Admin menu.
You no longer have to go to each blog to change the user’s role. It’s also 
much easier to see which sites a user is associated with.

Multisite User Role Manager

Ajax management makes it super easy to add users to a bunch of sites in the network. Does 1 things really well, more plugins should work like this.

Great for multisite user management

Made adding a user to 20 sites a lot easier than using WP's default interface for that (way less clicking around).

Much easier to assign a user to many sites

I spent about 30 minutes looking at different multisite user management plugins and all of them were either out of date, or tried to do too much. This plugin solved the exact issue I was dealing with: adding a user (with a specified role) to all of my client's subsites. 

Thank you very much. 

I wish you all the best,
Kevin.

P.S. the CSS for the admin screen where you add users to subsites was a bit off for me (in Chrome). The table did not fit the modal background (it hung off to the right a bit, and forced me to scroll even though there was plenty of vertical space). It doesn't bother me but it might bother some other users so I figured I would let you know. 

Excellent plugin - it does what it says!

Manage user roles for each blog from a single screen on multisite (WPMU) setups

room34

NEW IN VERSION 2.0.0: Users with a custom role will now only see the posts or pages they are assigned to. We’ve also streamlined the admin interface for easier configuration, and included additional instructions to help you get the proper capabilities assigned to your custom roles.
Custom Access Roles allows you to create, edit and delete custom roles for editing content. It was created to fill a need for a role editor plugin that is focused on providing easy-to-use admin tools for restricting content editing access. It is not concerned with restricting viewing access on the front end.
It is specifically intended for large sites with multiple content editors, where editors (by role, not individually) need to be restricted to only being able to edit specific areas of the site.
With this plugin, administrators of large sites have relatively fine-grained control over which user roles can edit which content, making it possible to manage a team of editors without concern that they will (accidentally or deliberately) edit content they should not have access to.
You can define a fully customized set of capabilities for each role, along with defining a specific set of post categories, pages, and custom post types to which those capabilities apply. For all other content, the role will have read-only access.
Custom Access Roles provides an easy interface for managing these roles and capabilities, with checkboxes for each capability grouped by the standard roles they’re associated with, plus checkboxes for each post category, page, and custom post type, presented in an organized hierarchy.

Custom Access Roles

Create custom roles with editing capability for only specific pages, categories and post types.

Multisite User Role Manager vs Custom Access Roles