While comments are already built into WordPress, there may be times that you want to offer your readers more options for commenting.
WordPress plugins (and third party tools) often can enhance your WordPress-powered website because commenters can, for example, sign in with Twitter or Facebook, upload images and videos, and even use HTML in their comments.
ContentRobot Recommends: IntenseDebate
IntenseDebate, another Automattic offering, is a feature-rich comment system that allows you to supercharge your community, increase reader engagement, and boost your page views.
Your visitors will enjoy being able to comment as a guest or sign in with Twitter or Facebook. You’ll also enjoy increased spam protection. Our other favorite features include comment threading and the ability to respond to comments via email.