I have recently completed work on my new plugin, designed to ease highlighting comments on wordpress blogs.
It gives you multiple classes per comment that describe the comment in detail, everything from whether the commenter wrote the post, or simply read it, to whether it's a trackback or a pingback.
You can download it from the wordpress.org plugin repository and read the release post, and install instructions on my site.
I'd love to hear feature requests and bug reports. It's pretty simple so nothing should be broken but I love getting feedback so anything is welcome.