Hover Zoom - Enlarge thumbnails on mouse over.
CONV. - Convert YouTube video to MP3, GIF or MP4
Image Max URL - Help find larger or original versions of images, including a customizable image popup feature
Softorino YouTube Converter - Download YouTube video & audio. Watch and listen offline
Hover Zoom+ - Google Chrome extension for zooming images on mouse hover - extesy/hoverzoom
You-Get - Command-line utility to download media contents from the web