This module adds a 'quote' link below nodes and comments. When clicked, the contents of the node or comment are placed into a new comment enclosed with special markup that indicates it is quoted material.
ImageCache_Profiles module allows you to set user profile pictures that are consistent throughout your site and allows avatars on the user profile pages to be a different size.
This module allows your site's visitors to send private messages to each other.
Adding functionality to your forum with contribs
Advanced Forum is a "glue" module that provides a layer between the core forum module and all all the various modules that add the functionality found in stand alone forum software.