A while back, I wanted to archive some data to dvd's and was surprised to find that the path that I wanted to archive was way bigger than what would fit on a dvd. So, I started poking around to see what was using all this space. I looked at my directory of digital photos first, but it wasn't the culprit, then I checked another directory and it wasn't the space hog either. During this process I kept wishing I had a utility that would start at a particular directory, and show me how much space each of the child directories was using. A tool like that would allow me to see at a glance where the space was going without having to navigate from directory to directory in Windows Explorer. So, I wrote SpaceHog. You can use it for free for as long as you like and share it with anyone you like. In the help screen I give you the option to make a donation to help fund future upgrades and also an email address where you can leave feedback.
Here's a screenshot: