How to Redirect a WordPress User to a Specific URL After Login Based on User Role

This snippet will help you to redirect a WordPress user after login, based on the user role.

Instruction
Add this code to your functions.php file.

<?php
   function redirect_user_on_role() {
      //retrieve current user info 
      global $current_user;
      get_currentuserinfo();
      //If login user role is Subscriber
      if ($current_user->user_level == 0) { wp_redirect( home_url() ); exit; }
      //If login user role is Contributor
      else if ($current_user->user_level > 1) { wp_redirect( home_url() ); exit; }
      //If login user role is Editor
      else if ($current_user->user_level >8) { wp_redirect( home_url() ); exit; }
      // For other rolse 
      else {
         $redirect_to = 'http://google.com/';
         return $redirect_to;
      }
   }
   add_action('admin_init','redirect_user_on_role');
?>

Related links
http://codex.wordpress.org/Roles_and_Capabilities