Are you giving a presentation soon and looking to receive instant audience feedback? Poll Everywhere is one solution. It is a web based technology that allows audience members to respond through text messages, the web, or twitter.
On the Poll Everywhere website, you can play around with the technology by creating your own poll (aka a question you would like to ask). There are two options for answer choices: open-ended or multiple choice. An open-ended poll will allow the audience to respond with anything. For multiple choice questions, you can type out answer choices or provide images or links as answer choices. If you have all your questions already typed out, there is a formatting trick to upload all your questions with just a few clicks.
In terms of cost, Poll Everywhere is free for audience sizes of less than 40 people. With more than 40 people, there is a monthly cost associated with the service. For Tufts classes of less than 40 students, Poll Everywhere could be considered as an alternative to clickers. Students would no longer need to carry around clickers and could submit answers through their laptop or cell phone. One downside to Poll Everywhere is that you do need internet access.
Poll Everywhere claims that their customers use their service for audience choice awards, market research, training comprehension checks, in class quizzes, texting questions to expert presenters and for many other occasions. If this sounds like a service you could use, check out their website. They have a good FAQ page which will likely answer a lot of your questions.