TreeSize Free (System Utilities - File & Disk Management)

TreeSize Free tells you where precious disk space has gone to. It can be started from the context menu of a folder or drive and shows you the size of this folder, including its subfolders. Each folder can be expanded in Explorer-like style to see the size of its subfolders. Scanning is done in a thread, so you can already see results while TreeSize Free is working. The results can be printed in a report.