Disk Space Analyzer (was Disk Inspector) is a disk scanning utility for Mac OS X. It scans any supported drive and generates a chart representing the file system usage.
Disk Space Analyzer is addressed to those who want to keep track of what, where and how large files are stored in his Mac disk. It integrates with familiar system tools, so you can preview a file using QuickLook.
You can start managing the files shown on the chart immediately after they appear on the screen and doesn't have to wait until the end of the scanning and analysis process.