Imagus - The extension is intended to complement image features that (I think) is missing from Opera by...
Hover Zoom+ - Google Chrome extension for zooming images on mouse hover - extesy/hoverzoom
Hover Zoom - Enlarge thumbnails on mouse over.
Image Max URL - Help find larger or original versions of images, including a customizable image popup feature
Thumbnail Zoom Plus - The official site of the Thumbnail Zoom Plus add-on for Firefox
iFrame - Link Viewer - Preview any link in a pop-up frame without leaving current page (instead of opening a new tab), eliminating the need to go back and forth to navigate to other links.