phpESP is a set of PHP scripts to let non-technical users create surveys, administer surveys, gather results, and view statistics, all managed online after database initialization.
But I found it's was uneasy for me to install and configure. This software require the application to be run on apache (recommended) but I dare to put it on IIS. Beside, it also need gettext to be install together with your PHP.
However it is listed as the 50 best open source for business even I found it still unstable.