I have implemented (by simply installing it) a new Comment system called intensedebate
Hopefully it will add more features to the comments bit of the blog..
- Comment Threading
- Commenter Profiles
- Reputation Points & Comment Voting
- RSS Readers & Tracking
- HTML Formatting
You need to create an account with them (or using OpenID), but that should allow you access to other blogs comments systems as well let me know if you are happy with it or not