Space Gremlin is a nice application that allows you to know how much occupied space you have on your computer and easily trash those files and folders that you don't use anymore. It offers a clear visualization of files that shows all the folders you have in a disk organized by size. The biggest ones will appear at the top in a sort of tree view. You will be able to explore folders, compress and trash files or entire folders very easily.
You can zoom in to view the files in every folder more closely, and then zoom out to return the previous view. If you wish to open a file to see what it is, you just have to use the "Show in folder" feature and then open the file. Moreover, you can also hide files or folders from your view that you know you don't want to erase by using the "Ignore" feature". The trial version will only allow you to scan popular places on your mac, such as Desktop, Documents, Music, etc, but not entire volumes.
In short, if you are looking for a nice application to clean your mac from unnecessary files, Space Gremlin may work for you.
v2.0 [Oct 17, 2014]
Fixed crash affecting Yosemite users.
Version 2.0 has finally landed. Space Gremlin has been rewritten from the ground up. New visuals let you easily find files and folders and navigation bar allows you to zoom in and out of folders quickly. New support for visualizing restricted files that were previously ignored. Better support added for Mavericks and Yosemite, but still backwards compatible with 10.6.
