Who it is for
Joomla site builders who need to link content to real Joomla users: assigning an author or contact person to an article, a team member to a project, or a manager to a record. The selected user comes straight from your Joomla user list, so there is nothing to keep in sync by hand.

Features

• User dropdown field type — adds a custom field that lets you select a Joomla user, in any extension that supports Joomla custom fields: articles, categories, contacts and more.
• Order the list — sort the dropdown by Name, Username or ID.
• Choose what the dropdown shows — display the user's Name, Username or Both in the selection list.

PRO options

• Select multiple users (PRO) — let editors pick more than one user in a single field.
• Filter by usergroup (PRO) — restrict the dropdown to users from a chosen usergroup.
• Same usergroup only (PRO) — limit each editor to selecting users from their own usergroup.
• Front-end display name (PRO) — choose whether the selected user shows on the front end as Name, Username or Both.

How it works
Install the plugin, or use Install from Web and search for "Joomill", then enable the User Dropdown custom field plugin.
Under Content > Fields (or any custom-fields-enabled extension), create a new field of type "User Dropdown" and set the ordering and label options.
Edit an article and select a user (or, in PRO, multiple users) from the dropdown.
The selected user shows on the front end.

Technical details
Custom field plugin for Joomla
Works in any extension that supports Joomla custom fields
Free version selects a single user, with sort and label options
PRO adds multiple selection, usergroup filtering, a same-usergroup restriction and a front-end name format