globalquiz.org - Difficult, multiplayer and multi-language trivia game.
Hover Zoom - Enlarge thumbnails on mouse over.
HugeQuiz - test your knowledge with a variety of quizzes about everything.
Imagus - The extension is intended to complement image features that (I think) is missing from Opera by...
JetPunk - JetPunk is the biggest online quiz platform that contains sports, geography, music, movies, and more regional or international information and database, created by H Brothers Inc.
Image Max URL - Help find larger or original versions of images, including a customizable image popup feature