I just had one this morning that was quite detailed and horrible, so I searched for this thread. I always try to type out my dreams and nightmares before I forget them. Sorry if it's a bit geeky, but this is how it was:

I had a developer friend from Japan who was working on a project to completely rethink customization on the Linux desktop, but had died before it could be finished. She had willed the reins of the project over to me exclusively, much to the chagrin of the Linux community. The desktop environment was considered by her to be too unstable and was thus never released to the public. I was the first, as far as anyone knew, besides her to have ever tested the new interface. In her last few years, as her health declined, she became a recluse and would only communicate with a select few others online.

The GUI was extremely amorphous to the point of, with a click, adapting to look and feel like Windows XP, Windows 8, Mac OS X, a Franken-GUI, KDE, e17, or your own imported creation. It came with an extremely intuitive editor for building your own GUI elements, and everything worked perfectly. I quickly noticed her creation was not unstable, but was rather a parting gift to me for when she passed away.

I made an interface that I could previously only dream of, in less than 10 minutes. I was impressed, and of course I eventually got the unavoidable urge to change my desktop background from its boring green-striped wallpaper. I checked the wallpapers, and was amazed. There were hundreds of images. The thumbnails loaded quickly and displayed everything from bubbly anime characters to nature scenes to images of cities with their dazzling lights at night. I was always complaining that overly-cute animes were annoying, so I figured she made the first 50 or so wallpapers incredibly colorful and cutesy as an in-joke. I first selected an image of a close-up of a fox kit. The preview, to my confusion, loaded the very same fox kit but much further zoomed away. I could just barely make it out among the sandy, mountainous terrain surrounding it and making up most of the full wallpaper.

Scrolling, I was able to zoom in closer to the kit. I accidentally scrolled too much, and I was able to see particles of dust on the fox's fur. I panned over, and could see every tiny ridge of the kit's wet nose. It was unbelievable. My friend had created digital images that not only looked lifelike, but that had an almost surreal amount of detail. I could zoom to my desired wallpaper being the entire mountain-face, or just the fox kit's eye, and have the same level of detail. Excited, I closed the image viewer (which she had created specifically for viewing the new file format the desktop backgrounds were in) and found a city scene. Again, once loaded the twinkling nighttime skyline was only a small section of the entire image.

Below the modern skyline was a mess of compressed garbage, leaking pipes, and steel sheets. Below that was an entirely different city, looking much like 1800s Britain. I was able to zoom into children running through the dark streets and prostitutes roving about. Out of curiosity, I pan all the way to the left edge of the image. The image automatically shifts 90 degrees, revealing a completely different scene that is an extension of the already impossibly detailed first one. I now can see a crowd of horrified people, watching as a gigantic cruise-liner sinks within eyesight of the aged harbor. There is a second cruise ship, dotted with faraway orange lights. I zoom into this source of light, which turns out to be the torches held by shirtless rebels slaughtering the upper classes on the ship. "What the..." I mutter as I can see people's glistening entrails being spilled onto the deck of the ship, and disembodied limbs lying at the end of trails of blood.

I try to pan away from this scene by again going left, which would have been the scene 180 degrees behind me when I had started. There is only a wet, moldy, dark cobblestone wall here. In red lettering to which I already knew the source, was written; "Is it all you had hoped it would be?" Under that was a haiku in much smaller lettering.
It read:
Out there exist things
No person should ever see
Meant for you and me