HardStat for Dashboard allows you to view the amount of free,used and total space for each of your drives.
With full icon support(mac only) and combination of graphical and text displays, Hardstat is the ultimate Hard Drive monitoring Widget.

Features:
-Combined Graphical and Text views
-Full icon support(Mac only)
-Built in update checker
-6 skins to choose from
-Powerful Cocoa backend(Mac only)

This download is for dashboard, version for Yahoo! Widget Engine also available at author's site.