The userplus module enhances Drupal's user administration and Organic Groups' subscription administration by allowing administrators to add multiple users at once, make multiple group assignments at once, and make multiple user role assignments at once.
It contains three color variations Blue, Green & Brown
To change theme colors, edit style.css in the theme folder, the theme in base.css is for basic styles, and a few colors that are good for all light bg, dark text theme (if you change this you may need to override them in either style.css or base.css).
D7 Version
Work is under progress, soon you will get the d7 version release.
For best Views & Rules integration, and bug fixes, please use the latest -dev version. - @hejazee
This module provides users with the ability to refer other users to a site they are registered at. When the new users registers, the referral is recorded.