Hover Zoom - Enlarge thumbnails on mouse over.
Subreddit Stats - Statistics for every subreddit.
Imagus - The extension is intended to complement image features that (I think) is missing from Opera by...
FrontPageMetrics - Daily updated statistics for every subreddit on Reddit. Top subreddits, new subreddits by date, all subreddits, trending subreddits, plus more Reddit stats
Image Max URL - Help find larger or original versions of images, including a customizable image popup feature
Redective - Find information about Reddit users