LimeSurvey – an easy FOSS PHP survey application

Cool features:

• Support for exporting questionnaire survey using queXML which supports DDI
  http://docs.limesurvey.org/tiki-index.php?page=Exporting%20a%20survey%20structure&structure=
• Export into other formats like Excel and SPSS:
  http://docs.limesurvey.org/tiki-index.php?page=Exporting%20Results&structure=
• Other stats and outputs
  http://docs.limesurvey.org/tiki-index.php?page=Statistics&structure=

Demo: demonstration site

user: admin
pass: test

Download:

Manual:
http://docs.limesurvey.org/English+Instructions+for+LimeSurvey

(Thanks Jason for the link)