There are some others that allow you to conduct some surveys for free, but again, if you want to do heavy duty surveys, you will probably want to upgrade to a paid account. Some free services restrict either the number of surveys or the number of responses you can receive.
If you are interested in only conducting a small number of surveys, but expect a large number of responses, you might want to look at http://www.questionpro.com/ or http://questionform.com which allow 2 surveys per month with unlimited responses. On the other hand, and I haven't tried this one, http://www.esurveyspro.com lets you create unlimited surveys with unlimited responses but seems to be ad supported, so if you don't mind having someone else's ads displayed in your survey, this seems to offer a lot of flexibility.