GreatNews

I've tried many RSS aggregators but the one I like most is GreatNews from Curio Studio.

Here are some tips I've learned from using it for a while:

• Ctrl+R: Mark feed as read
• Ctrl+T: Create new tab
• Middle click
• Feeds: Opens originating page
• Posts: Opens post in current tab
• Links in posts: Opens link in new background tab
• Tabs: Closes the tab
  
• Tools → Options → Reading
• Check "Mark previous feed as read when switching feeds"
• Do not sort by date (or anything for that matter). This really slows it down.
• Tools → Cleanup... : Cleans up unread posts