★★★ Free for a limited time ★★★
Monotony is a feed reader doing exactly one job: Subscribe to RSS and Atom feeds, Monotony checks for news every minute. News will be displayed on the desktop as notifications, featuring the headline and a summary (if there's one). To read a news item in your default web browser, just click on the notification.
There is nothing else. No Google Reader sync, no frontend, no possibility to customize it. Monotony runs as a menubar app or, if you choose, invisible in the background. That's all.
If you want, you can use Monotony together with Growl, the desktop notification system. However, you don't have to.