Strutta: Create not just polls, but online contests as well. Strutta allows teachers to moderate all student content before being posted online.
Flisti: A simple poll creator that allows users to share with popular social networks.
Obsurvey: A great site with a wiki-style interface that allows users to create surveys with different styles of questions, such as multiple choice, true or false, and others.
Survey Monkey: One of the best online sites for creating surveys. The free version offers 10 questions per survey, up to 100 responses, and real-time results.
Polldaddy: Similar to Survey Monkey, with a nice user interface.
Vorbeo: An easy-to-use site that lets users embed a poll directly into their blog or Web site.
Text the Mob: Good site to use with a large audience. Allows users to text in their responses via a mobile device. Built-in filtering soon to come, which would be ideal for schools.
Insightify: A great collaborative Web site for creating online surveys.
Yarp: A fun site to use for creating simple surveys that generates a unique URL.