The Feedback module allows you to create and conduct surveys to collect feedback. Unlike the Survey tool it allows you to write your own questions, rather than choose from a list of pre-written questions and unlike the Quiz tool, you can create non-graded questions. The Feedback activity is ideal for the likes of course or teacher evaluations.
The Feedback module is included in Moodle 2.0, but disabled by default.
The long term plan is to replace Feedback with a new module combining the best of Questionnaire, Feedback and Survey. See Development:Survey 2 brainstorm