Impressive : add a single javascript line from JS-Kit and you get a full comment system without any other coding or server side stuff needed. There are even several options and settings, and the whole comment engine is Akismet enabled to make sure you get no spam.
I'm not sure how convenient and easy things are when it comes to moderation, but still, this is quite neat. I would probably even consider using it if I had a blog on Blogger and their terrible comment system.