Simple Forms

How do you build forms?  We are tasked with building a toolkit that's pretty framework agnostic, meaning it should work in asp.net webforms, asp.net mvc, castle monorail, or any other framework.  It needs to only be tied to html, meaning all it does is generate the html for a form that has nothing to do with any framework. 

Whatever "it" is,  needs to generate forms, in an intelligent way, not just CRUD forms that have no life.  By intelligent, I mean they need to fit the destination application in look, feel and behavior, and they are not generic in any way shape or form, other than that they have to fit most of the cases for the destination application. 

How fast can you build forms? And by speed I mean, what's the least amount of code you can write to get no less than 100% of the desired form functionality.  This includes any field validation, etc.