Add a instant validator for WordPress comment form, instead of sending users to default error page.
Avoid those pesky blank page with an error message like "please fill out required fields" then loosing your/users comment info.
SiteBrains blocks spam posts using a completely configurable set of rules. Both interactively as the user types and on our servers upon submission.
Add extra features to your wordpress comments like ajax posting, email notification on reply and field validation.