If you take a lot of photographs or videos, if you have a lot of MP3’s or if you keep downloading the latest Humble Bundle games the chances are that you will be starting to fill your hard disk and get short on space. It can however be difficult to know where all that space has gone to and difficult to figure it out.
WinStatDir or Windows Directory Statistics is an disk usage statistics viewer and cleanup tool for various versions of Microsoft Windows. In other words point it at your disk drive and it will tell you how big directories are and give you a clear diagram representing this. It makes it obvious where the big directories, file types and space hogs are and lets you clean them out and make space.
WinStatDir is written for Windows but there is a similar program for OSX called Disk Inventory X and for Linux with KDirStat. If you start to run out of space these programs should be your first port of call.