My first experience with dreamplanes was a movie, that I don't remember the name of, where a guy with psychic abilities gets recruited into a program where they use a machine to allow psychics into other people's dreams. At first they this is done to help people with problem dreams, then he develops the ability to enter dreams without the machine and has to save the president from one of his coworkers.
Besides the plot, the interesting thing about the movie was that while in a person's dreamplane, they had the ability to create any item they needed and they were even able to change their form.
This seems like a good adventure or side adventure concept, where they can get anything they need, but there is quite a good chance that anything could turn on them, becoming a nightmare. A character that they believed to be another visitor to the dreamplane could turn out to be a part of the dream, and upon leaving they find that this person that they have bonded with is nothing but a dream.
The person you took out of the dream with you is still a dream-being but by releasing it into world you unleash the chaos of dreams. Which then reminds me of an anime movie called paprika, where people use technology to view and record a person's dream. Eventually it releases a crazy person's dream and an evil person's dream into the world. Long story short, it took a giant naked ghost lady with multiple personalities to fix things.
where was I?
Oh, right! While in the dreamplane, you can conjure any item you need and even manipulate the surrounding area. Maybe to add to the mess, you have to worry about your sanity if you go into a crazy person's dream, or maybe nightmares have some sort of corrupting effect on people.
I may just write a campaign based on the ideas here... except that the people I play with are readers... >.<
Well, maybe they will forget...
Anyway, does this rant inspire you? Does it make sense? Does it seem pointless to you? Comment!