Key features:
"Visual tracking of hard drives and view the size of all folders and files
"Print a report to Excel, HTML, XML, text file, etc.
"Fully customizable file search to search and archiving of large, old, unused and temporary files
"Search on multiple disks or entire servers
"Search for duplicate files, in addition, to check the MD5 hash sum
"Statistics about file types and file owners on directory level
"The ability to save data in XML file to load later
"Support for Unicode names for files and folders
"Extension for Windows Explorer
"Viewing the results during scanning
"Inclusion and exclusion of specific files and folders while scanning
"Print directory contents
"Support the Explorer context menu inside the program window

Home:
http://www.jam-software.com/treesize/