Mac: Flipping between tabs to get to your Facebook notifications and messages can get annoying, especially when chatting with someone from your browser. Current for Mac integrates Facebook with your desktop, so you can reach everything without leaving your current browser page.
Once installed, you'll get your notifications, inbox and friends list from the menu bar. Anything you open can have its own window, which could lead to clutter, but the app is particularly useful for messages that require more constant attention. You can also swipe through photos, which is a much nicer way to browse.