Imagus
The extension is intended to complement image features that (I think) is missing from Opera by…
18 Alternatives To Imagus
ImagePreviewer
This extension shows a popup with an image preview when hovering over link that points to an image file or a page with an image.
Shaarli
Shaarli is a minimalist link sharing software you can install on your own website
Thumbnail Zoom Plus
The official site of the Thumbnail Zoom Plus add-on for Firefox
Zoom
Zoom unifies cloud video conferencing, simple online meetings, group messaging, and a software-based conference room solution.