So I really dig Alex King’s Popularity plugin but I’m disappointed that he’s not updated it for WP 2.5 yet. So since it took me forever to find the information on fixing it I’ll post it here. WARNING if you break it, its not my fault! 
Also FYI this is a temporary fix until the actual plugin is upgraded, this just gets things working, its not perfect.
Open popularity-contest.php and scroll down to line 59. Replace require(’../../wp-blog-header.php’); with require(’../wp-blog-header.php’);
If you get an error (most likely with a new installation) about a Table not existing, the following code should be run in phpmyadmin or any other SQL database access program (usually the wordpress table prefix is wp_ make sure you change this to reflect your local settings):
CREATE TABLE IF NOT EXISTS <wordpresstableprefixhere>ak_popularity (
post_id int(11) NOT NULL,
total int(11) NOT NULL,
feed_views int(11) NOT NULL,
home_views int(11) NOT NULL,
archive_views int(11) NOT NULL,
category_views int(11) NOT NULL,
single_views int(11) NOT NULL,
comments int(11) NOT NULL,
pingbacks int(11) NOT NULL,
trackbacks int(11) NOT NULL,
last_modified datetime,
KEY post_id (post_id)
) ENGINE=MyISAM;CREATE TABLE IF NOT EXISTS <wordpresstableprefixhere>ak_popularity_options (
option_name varchar(50) NOT NULL,
option_value varchar(50) NOT NULL
) ENGINE=MyISAM;
