DISQUS is a very tidy commenting system that I have just enabled on this blog, Invertebrate Diaries and In Defence of Reason. DISQUS has some very neat features, the main one being the ability to track all of those comments you have made to blogs all over the interweb from one place (as long as those blogs use DISQUS).
You can sign into DISQUS using your Facebook, Twitter or OpenID credentials, or make a new account. It also has some pretty good spam filtering and comment management options. So I'd ask you to have a go and see what happens!