We were investigating polls (e.g. topics of contention, user feedback) on our facebook fanpage a short while ago and there are a few apps which accomplish this task. However, I think a better idea would be to develop a polling platform on our actual website. This way, you market the poll on facebook and direct fans to the poll on your website. The poll then generates traffic directly onto your site, generating organic link backs and creating content for future organic searches. This has a lot of very positive implications from ranking well organically. Is this plan rooted in reality? Does it sound feasible?
Another aspect to consider is the annoyance of having to install a facebook app to vote for a poll, that would deter from voting in the first place..