You could try the FormsGenerator. It's an Opensource .NET FormsGenerator, which can be used in any CMS. It has a WYSIWYG designer and functionality for designing advanced forms with multiple pages, validators and merged cells. It's also highly configurable for deciding which form elements should be available to the users/editors. Last it has functionality for integrating with the Editor/Administrator GUI through WebServices.
Check it out on http://formsgenerator.sourceforge.net