Reeder for Mac, a great Google Reader client for RSS feeds, has a ton of keyboard shortcuts that let you fly through most of what you do much faster. They’re also very Gmail-like, so P/N will move up and down between subscriptions and folders, while J/K move down and up through each article.
⌘-⌥-← (Command-Option-left arrow) will enable Reeder’s “Minimized layout” and hide the reading pane, so you can hit the right arrow to open an article in Reeder or Return to open it in your default browser. ⌘-⌥-→ will return Reeder to its “Classic layout” by expanding the reading pane.
Reeder has quite a few more shortcuts for everything from search (called ‘Filter’), starring articles, and even adding and managing subscriptions. Check out Reeder > Preferences > Shortcuts to view the full list and customize your shortcut keys.