TreeSize Free has saved me hours of boring tedium trying to find large files in folders of our clients. I often get customers come to me asking why they are running out of disk space, or I get suspicious when a backup of user data grows by a gigabyte over night. Its not always the users fault either, Software giants such as Adobe, Apple and Skype have a habit of storing data in users roaming profiles, making them grow to sizes that cause slow login on computers. Treesize allows me to locate these and resolve problems quickly.
Download it here: http://www.jam-software.com/treesize_free/