Use the space bar, Luke
One of the things that’s non-obvious about NetNewsWire is that the space bar is the best way to read the news.
It goes to the next unread headline. But first it scrolls the description pane if needed.
This way you can motor your way through the news. Totally easy.
(Update 3:17 p.m.: note that the space bar works only when the subscriptions or headlines pane has focus. So you may have to click with the mouse first.)
Another thing: I get a fair amount of email saying how cool it would be if folders were supported in the Subscriptions pane.
And of course they are—only they’re called Groups. Choose New Group from the Subscriptions menu to create a group. Then you can drag and drop your subscriptions to organize them however you want.
One of the cool features of groups is that if you select the group you see the unread headlines for all the feeds the group contains. This way you can set up mini-aggregated views for certain topics.
For instance, here's a screen shot of my personal copy of NetNewsWire with my Technology group expanded.