Poll Everywhere released a very nice update, support for images and equations. Now you can put images into your polls and have students vote on the images. Another part of this update is the option to include mathematics equations in polls. The video below provides an overview of the updates.
Image Support for Multiple Choice Options from Poll Everwhere on Vimeo.
Applications for Education
The image voting option could be a good way to create surveys or polls in which you ask students to identify plants, animals, and other objects. The mathematics inclusion option will allow you to create multiple choice polls in which students have to select the correct equation.