From version 7.x-3.x, you could now attach fields to Flags, this module, Flag forms, provides a form for filling out these fields.
The development of this module was done by mooffie and published on Github, and it has now been moved here to Drupal.org, to further development.
The module was first named flag_form and published on GitHub, and now moved to drupal.org. Here there are a existing module with that name, therefore the name has changed to flagging_form.
Version number change
20120809: To reflect the dependency on Flag 7.x-3.x, the version number for Flagging form is starting from 7.x-3.x.
This module is sponsored by Wunderkraut.