Flag Field

This module provides a custom field type that allows you use flags with your own custom FieldFormatters. This provides more flexibility that the default way of adding flags a extra fields, for example, you can use different theme functions on a per display mode basis for your flags. The module provides several build in theme functions and templates, although the css etc. isn't provided. So it's not quite an out of the box solution yet.

To use this module:
1) enable
2) add flag field to a content type.
3) configure (select which flag you want to use, select which formatter you want to use for each display mode).
4) copy templates to your theme and add your own styling.