Mac: The most hard drives and storage devices you connect to your Mac the more difficult it is tell how much space you have available on any of those devices to store files or back up your data. FreeSpace for Mac is a tiny menubar utility that can show you how much space is available on all local, connected and network drives with a single click.
Once installed, click on the menubar icon for FreeSpace to see all of your drives, organised by local drives and partitions, USB and Firewire connected drives, and network drives that are attached but stored on another computer. FreeSpace also allows you to eject any connected or network drive by clicking an eject icon next to each drive name, much like previously mentioned app Ejector allows you to do. FreeSpace is $0.99 in the Mac App Store.
FreeSpace [Mac App Store]