The CGI::Application::ValidateRM module utilizes HTML::FillInForm to fill in values in the form if portions did not pass validation. Basically, it utilizes HTML::Parser to go through and find the elements and match them to values. It's used because the assumption is that you've built your form into an HTML::Template, and that way you don't need to put in program logic into the form.

Seems another good candidate for using FillInForm would be to populate a form with values grabbed from a database… I should look into that as well!