Plugins can extend WordPress to do almost anything you can imagine. Here are the free plugins I have created.
Allows "permissions" to be set for xprofile fields.
You can change your author base permalink to anything you want like 'members' or 'users' instead of 'author'.
This plugin themes the WordPress login, registration and forgot password pages according to your current theme. It replaces the wp-login.php file by using a page template from your theme. Also includes a widget for sidebar login.
This plugin allows you to theme a user's profile based upon their role. It even includes custom roles if you have any.