Architecture: Where to Put Forms?

[eluser]fireproofsocks[/eluser]
This is an architecture question: where do you put the code that makes your forms? I'm always a big fan of leaving as much open to the front-end designers as possible, but forms are areas where the MVC architecture gets blurry. I'm wondering how others handle forms in their code... do you guys create a separate library-type file that you can use with different controllers? Or do you put the form code in a view? Just curious...