Discussion Column is intended to organize conversation in the list item without need to enable list versioning. Component allows entering rich text with formatting, images, tables, hyperlinks, etc.
Downloads: 121518 - Shareware

Unlike SharePoint's out-of-box discussion board feature and the range of third party tools, HarePoint Discussion Board allows real-time discussion by showing all new posts, replies and comments in time of their appearance without page reloading.
Downloads: 135271 - Shareware