This evening I received an email from a teacher that was looking for a survey / poll creation tool that her students can use without having to create an account. Here are two options that fit that bill.
Yarp allows you to create a simple one question survey or a simple event invitation. To create a Yarp survey select "survey" on the homepage, type a question, then select your answer format. All answer formats present only two options along the lines of "true or false" or "yes or no." Each Yarp survey is assigned its own unique URL for you to distribute to the people that you want to complete your survey. Yarp invitations use the same format styles as Yarp surveys.
Flisti is a free and easy-to-use polling tool. Registration is not required in order to create a poll with Flisti. In fact, registering doesn't seem to be an option at all. To create a poll using Flisti just enter your question, specify some answer choices, then click "create new poll." Your poll(s) can be embedded into your blog, website, or wiki.
Applications for Education
Both of these tools could be good for students to use to quickly collect data about their classmates' opinions on any number of topics from politics to pop-culture to taste in food. An economics lesson from the Buck Institute for Education that I used for a few years required students to develop cafeteria menus and order supplies for the cafeteria based on the ordering patterns of their classmates. In that situation a simple survey tool like Yarp or Flisti could help students develop and recognize ordering patterns.