If you have the regular version of NetNewsWire, you can drag and drop a headline or URL onto the summary view to view the corresponding webpage there. This works great if you change to widescreen view and have all your subscriptions and headlines on the left and the summary view on the right.
You can also drag and drop URLs from the desktop or Safari.
Mac OS X Hints
http://hints.macworld.com/article.php?story=2007022318394316