another good place to try n search for php scripts is
http://sourceforge.net/search/. just search for something like 'php poll' (check 'require all words' for better results, n choose projects that have high activity percentile)
i've searched for u, n i found quite a few:
http://osp.serie-a.de/english/features.php
http://prestopoll.sourceforge.net/
http://sourceforge.net/projects/phpollster/
http://sourceforge.net/projects/adpforum2/
good luck.