DaisyDisk not only helps you find space wasters, but makes it easier to decide whether the files are apt for deletion or not.
The sidebar panel provides basic information about files and folders, but in some cases this is not enough. You can preview content of any file or folder using the built-in Quick Look, just like you do in Finder. Simply point to an object and press Space or right-click and select Preview from the menu.
The preview uses the same Quick Look that powers Finder, so it picks up any plugins installed on your system.
Preview works on the disk map, sidebar and Collector items.