Nauseate yourself, others with YouTube's hidden 'warp' feature
Explore YouTube videos in space, kind of.
Put this feature in the category of neat looking but potentially headache inducing. It's a recently-introduced YouTube feature that lets users view videos in a floating array of thumbnails. Users of Digg's swarm visualization will feel right at home, as both share a slightly similar interface (albeit Digg's is a little more useful).
To access the warp mode click on the full screen button in any YouTube video (the one on the far right) and then move all the way over to the left to the strange triangle-looking button. Clicking it zooms the video out into a black space with tiny round video thumbnails. Holding your mouse over any of them will pull up other similar videos--a process you can continue forever, or until you hit a dead end (marked with a red border). If you've ever used Quintura's video search, it works the same way.
One thing to note is that this feature only works from videos watched on YouTube, and not embedded clips. It also doesn't seem to work yet with videos that have YouTube's overlay ads in them.
Update: Gallery of warp videos here.