Like xspazx said, google would frown upon that and it may or may not be legal to actually do.
But, its entirely possible to make a feature add x points inside of a php script that then redirects for a banner ad that is not google.
All u'd have to do is make a simple php file something like:
redirect.php
<?php
// ######################## SET PHP ENVIRONMENT ###########################
error_reporting(E_ALL & ~E_NOTICE);
// ##################### DEFINE IMPORTANT CONSTANTS #######################
define('THIS_SCRIPT', 'redirect');
// #################### PRE-CACHE TEMPLATES AND DATA ######################
// get special phrase groups
$phrasegroups = array();
// get special data templates from the datastore
$specialtemplates = array();
// pre-cache templates used by all actions
$globaltemplates = array();
// pre-cache templates used by specific actions
$actiontemplates = array();
// ########################## REQUIRE BACK-END ############################
require_once('./global.php');
require_once('./includes/functions_vbplaza.php');
// ################################################## #####################
// ######################## START MAIN SCRIPT ############################
// ################################################## #####################
// increase the user's points
vbplaza_quick_add_points($vbulletin->userinfo, 100, '');
// jump to the url
header("Location: " . $_REQUEST['url']);
exit;
?>
I havent tested that, but it should work. Then when the link is created for ur ads, it will need to jump to this php file like so... <a href="redirect.php?url=linktogoto"><img src="...."></a>
-CMX