What's the strangest thing you've ever seen on the internet? This question is more along the lines of things that made you stop, think, and just question what you were looking at. The more abstract the better.
For me, it was hell.com's "chaos" thing. It was a huge puzzle, one flash puzzle leading to another. But it was confusing because you never really knew what was going on. Very dark, mysterious. Very cool. It's not around these days, unfortunately. It creeped me out.