I had some spare time so I decided to browse some mailing lists I had subscribed to. And keeping track of replies can be hard if you don't browse lists daily. So I created this rule in Mail.app:
If [all] conditions are met :
[To] [Contains] some.list@listserver.org
[Subject] [Contains] Re
[Message content] [Contains] YourName
Then I added some Actions to it. I used a color and a sound, as seen in this screenshot.
Notes:
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020920061541139