Mentimeter. I checked it out to see if it was comparable to something like Poll everywhere. I liked it, but I don't see it being something I would use frequently. Mentimeter does allow you to create a poll and select options for the answers. It is an instant response, you can see everything people select on a screen as soon as it is submitted. It can be used with a cell phone or with a computer. With a cellphone, students can use their browser, input a code and select the answer. The same can be done with a computer browser as well. It is a free service.
The positive if Mentimeter, the number of respondents can be unlimited. The negative, you can't save surveys. On sites such as poll everywhere, you can create an account and save your polls, you just have a limited number of responses available. Mentimeter responses are only choices. Participants cannot fill in the blanks, so if you are looking for ways to get more than a yes, no, or a multiple choice answer, don't use the program.
Mentimeter has a page with ideas for use developed for teachers. Responses are anonymous but there are several things you could use this tool for.
Quick exit slips: Have students do a poll to see what they understood from class that day.
Topic polls: Perhaps you teach a class where the kids have a say in the content. You could survey students to see the next step.
Yearbook surveys: If you sponsor the yearbook, like I do, you could do a survey to gather responses for a page.
Warmups: Have a survey ready upon arrival and require students to answer them to see if they retained prior knowledge.
Predictions: If you teach an English class and are reading a specific title, you can have students guess the outcome of the book or predict what is happening next.
The Mentimeter site offers a few more ideas for use.