Comments can be added to any web page using the Disqus embedded commenting system.

http://disqus.com/

Disqus is an online discussion and commenting service for websites and online communities. The company’s platform includes various features, such as social integration, social networking, user profiles, spam and moderation tools, analytics, email notifications, and mobile commenting.

Disqus is featured on many major publications, such as Engadget, CNN, Fox News, Daily Telegraph and IGN and about 750,000 blogs and websites

You can try out the comments below - note: each site can have its own security and login settings. This example allows user to add a comment by supplying their email address (without verification). You can restrict comments to authorized users or you can approve comments individually.