Earlier this year I played around with the IntenseDebate Plugin from WordPress. It ended up causing me a lot of headaches on the administration side so I disabled it and went back to the default WordPress set up. The problem with that approach was I set the bar too high (due to Spaming through IntenseDebate) to comment and it meant that I had to manually read and approve every single comment on the site which lead to me banning people. I’m now going to try a new system called Disqus. You can now use your IDs from Twitter, Facebook, and Open ID to leave comments. Improved features include threaded discussions, the ability for the community Vote comments up and down and more cool features. So give it a go.
You may have to register again like I did.
Also, once you log in you may have to leave where you wanted to comment and then come back in order to comment.