This will sound like a shameless plug but its a tool I just love! PicLens by CoolIris. It is an add-on that installs on your desktop for a deep integration with your browser.
Each time you land on a site with thumbnail images, CoolIris adds a tiny arrow in the corner of those images that launches their 3D immersive environment. The app loads all the media assets it can find on the page and lets you wander through them by moving along a 3D wall. Not only does it display static images, but plays videos in-line. You can use it for a much richer experience when looking through YouTube or Google images.
The coolest feature is the built-in search integration. While in the full screen 3D environment, you can search for media on 8 popular search engines.
Con: CoolIris needs to be media-aware for it to work with most sites. Developers will be pleased to learn that the company offers a free quick wizard to "CoolIris"-enable your own website.
Check out the introduction video: