I'd like to request a feature in a future version of WordPress: threaded comments. Right now, the only ways to respond to comments is to email the commenter or post another comment on the original post, which is either hidden or disjointed. Ideally, making it a more conversational experience would be nice; the comments approach on LiveJournal comes to mind as something that works fairly well.
I know there is at least one plugin available for this sort of functionality, but unfortunately it is not very customizable in terms of how the threads appear. This design may work well with the creator's own site design, but it doesn't work well with other themes. (I'm sure this could be edited, but that would require knowing how the script works and how to adjust it, which I'm not comfortable with doing myself.)