opinion polling code

Hi I'm looking for some free opinion polling code using PHP and MySQL. I've checked a number of scripts and they haven't been up to scratch - I'm just after a simple poll that allows a user to vote once (selecting yes or no) and then for the remainder of their session they can only view the poll results (i.e. not vote again). Tricks like hitting refresh to resubmit the vote shouldnt work, and the results need to be shown as a bar graph - if anyone knows of a good script, please let me know. I'm trying Sympoll but it's not working properly and the guy's site is down (www.ralusp.net) thanks in advance Lucas Young