Online survey

Last few weeks I work on the project for PhD student in England. She needs a reliable online survey application which will reside on her web server. It should be open source, php based system and it should support MySQL database with the possibility to give each repondent his/her own username and password. I first tried out LimeSurvey, but it uses tokens for restricted access which are not sufficient for this poject. Later I found phpESP and as far as I have tested it, it should be perfect for the job. However, I found it will be harder to make it look good. Cross your fingers!