For a while I disagreed with comment systems with the assumption that someone would email if they had something relevant to say. This is naive. Interaction is far more important: if it only takes 5 seconds to comment then plenty of individuals will contribute and there is no need for hard mental operations. Once there has been a premature commitment, from the initial interaction, users are more likely to return.
So which comment system to use? Drafting my own is not an option. It has been done thousands of times before and I do not want to support commercial global identifiers that change over time. Is it worth the effort?
A couple of comment systems
Disqus integrates with Facebook/Twitter and is used by Wired magazine. Known for keeping up with developments from other social networking sites.
Intense Debate targets blogging platforms like WordPress, Blogger, Tumblr. I previously used this system while helping the Cambridge Tab last year. It was easy to administer through Wordpress.
My choice
Disqus won through because of its clean interface. Installation required a single JavaScript snippet at the bottom of my article pages. Further integration is possible by providing Disqus permalinks and unique article IDs to enhance their interface.

Comments