Open source survey application
LimeSurvey (formerly PHPSurveyor) is an open source survey management application written in PHP. It supports some advanced survey setup including branching logic, custom templates, and a wide variety of question types.
We've used this for several surveys and performed more detailed data analysis by exporting the data and plotting with the R programming language.
See limesurvey.org for more information, or contact us if you would like some commercial assistance.
