TheFolderSpy is described as 'Ever found yourself in a position to know about a change in your hard disk?'. There are four alternatives to TheFolderSpy for Windows, Linux and Mac. The best alternative is WatchDirectory. It's not free, so if you're looking for a free alternative, you could try DaemonFS or Watch 4 Folder.
Watch 4 Folder is a simple to use, small and portable tool to monitor folders and file activities. You can set a monitoring process with just 4 simple quick steps and then minimize the tool to the system tray.