I know we already have ratings available for the articles, but how about rating the comments.

It would work like this - a user reading a comment he likes would click a button "vote for this comment" or something like that, which would be embedded in the comment's area. After a certain number of votes have been accumulated for a certain comment, it would have a different CSS class assigned to it's containing element. Now it would be possible to apply different style rules for comments with higher ratings. (like a vary popular comment would be highlighted in bold red, or something like that...)

Opher.

This feature would be nice. I have seen some sites implementing a rating of comments using scale 1-5 as well. Then you could either choose to sort comments by highest rating or latest...?

Look for example at this site: (scroll down to see how they implement comments, they are even threaded):

http://www.technologyreview.com/read_article.aspx?ch=specialsections&sc=emerging08&id=20243

This is a great idea!  I have been thinking about having users vote on comments.  This would be a great addition for the Property Agent as well.