TreeSize - TreeSize tells you where precious disk space has gone to.
Birch - Find the best credit card for your spending.
WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
The Roll by EyeEm - Organize your iOS Photos automatically
SpaceSniffer - SpaceSniffer is a freeWare (donations are welcome) and portable tool application that lets you understand how folders and files are structured on your disks.
Cleanz - Simple and beautiful way to clean up your photo library