Survey monkey is really easy and you can set more advanced metrics. I have used it in market research and it has everything you need and you can even do A/B testing for different questions. Good luck!!
I did a search for "polls" and found these.
Rather than a specific site, I recommend using a Wiki where everyone can add, change, and share the site equally in a public or private environment. Little effort is necessary to set things up just the way you want them.
Have a look at pbworks.com