ScreenshotMenu is a screen capture utility designed for Mac that sits on your Menu Bar and enables you to take snapshots of your desktop. The application is very simple to handle, uses minimum CPU resources, and immediately captures the screenshots you need.
After you launch the program, an icon will be displayed in your Menu Bar. From there, you can choose between four screen capturing methods: Window To File, Area To File, Window To Clipboard, and Area To Clipboard.
Another good aspect is that it comes with an option to automatically open the saved snapshots within the Preview app (Mac's default image viewer).
Sadly, the utility is missing some features. For example, it supports only one output format (PNG), it doesn't provide you with a timed screenshot mode (takes snapshots of your desktop after a defined period of time), and it doesn't offer you an option to define global hotkeys for taking snapshots.
Briefly, ScreenshotMenu is a simple yet helpful program for Mac. So, I'd say it's worth a try if the aforementioned disadvantages are irrelevant to you.