From JAM Software:
Every hard disk is too small if you just wait long enough. TreeSize Free tells you where precious space has gone to.
TreeSize Free can be started from the context menu of a folder or drive and shows you the size of this folder, including its subfolders. You can expand this folder in Explorer-like style and you will see the size of every subfolder. All results can also be drilled down to the file level. Scanning is done in a thread, so you can already see results while TreeSize Free is working. The Explorer context menu is supported within TreeSize, as well as the usual drag & drop operations. The disk space tool now also includes the main feature of our discontinued freeware NTFSRatio: TreeSize Free can display the NTFS compression rate.
What's new in this version:
Version 2.5.1 increased speed when expanding many folders and files. The progress of a scan is now shown in the Windows 7 taskbar. Now able to show the NTFS compression rate in the directory tree (NTFSRatio deceased). Added new option allows to show compressed folders in blue, partially compressed in dark blue.