Imagus - The extension is intended to complement image features that (I think) is missing from Opera by...
NexusFont - Choose and manage your fonts with Nexus Font.
Thumbnail Zoom Plus - The official site of the Thumbnail Zoom Plus add-on for Firefox
Font Viewer - Font Viewer is an application which does exactly that - it views fonts!
Image Max URL - Help find larger or original versions of images, including a customizable image popup feature
Font Manager - Simple font management for GTK+ desktop environments