Google Usenet subdirectories could be improved. Except for the "Activity" greenbars (which happen to be misleading or at least not very accurate), there's not much you know about these groups from this list, meaning you need to click on each group to know what's inside. The fake screenshot below displays to easy additions to make that list more useful: it tells apart new groups, and shows how much total and new posts there is within each group. New posts could be either a reasonably short period of time (say, one week) or based on user profile if/when Google Groups features personalization.

12/12/02 update: they provide this kind of meta information in their directory with the number of links per category.