NetNewsWire and NetNewsWire Lite allow you to read through lots of new site articles without taking a lot of time to do it.
I've recently started using NetNewsWire and NetNewsWire Lite for the Macintosh by Ranchero Software.
These packages provide a simple UI for reading through large volumes of new information being posted to sites. By using the RSS specification, they grab syndication feeds (information that is made available by the web sites, usually in an automated fashion) and format them for easy display on your machine.
Once downloaded, you can read through the summaries (if the originating party puts them in there), jump to the article directly, mark as read or unread, etc.
The UI is very familiar to anyone who has used tri-pane news readers in the past and provides a very adequate user experience.
The Lite version does most of what the full version does, except post to WebLogs.