TreePie : a simple way to display disk usage. It shows the distribution of size in a tree of directories by using an interactive multilevel pie (sunburst diagram). Really small and simple.
The perfect lightweight app: does one thing, and does it well. The download is only 187kB (including sources), the binary is only 70kB. It scanned quickly, and provides a profoundly easy way to click around to find the worst users of disk space.
Very nice way of showing the disk usage. Excellent!!!