WinDirStat - WinDirStat is a disk usage statistics viewer and cleanup tool, inspired by KDirStat.
YoutubeMultiDownloader - Just like its name YouTube Multi Downloader, it is an online website for downloading the videos of downloading without using any video download and accelerator.
WizTree - WizTree quickly finds the files and folders using the most space on your hard drive. It scans the MFT (Master File Table) instead of crawling the entire disk which makes it very fast.
KeepVid - A free web application that allows you to download videos
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.
SaveFrom.Biz - Convert YouTube video URL to MP4 file and download it to your device. SafeFrom is the best YouTube video downloader and converter.