On the subject of programs embedded within programs, could you not say that even imagination, writing and reading, the making and watching of movies and all other similar imaginitive, storytelling arts lead to/are acts of simulation, and increase the probability of said universe?
Have you ever read Heinlein's novel "The Number of the Beast"? The main characters invent a device for traveling between universes, and when they use it, they end up in the worlds of their favorite sci-fi novels. They end up concluding that universes are created by the act of imagining them, and that there must be a world in which they themselves are fictional characters thought up by some author.
So I'd intended this story as a bit of utterly deranged fun, but it got out of control and ended up as a deep philosophical exploration, and now those of you who care will have to wade through the insanity. I'm sorry. I just can't seem to help myself.
I know that writing crossover fanfiction is considered one of the lower levels to which an author can sink. Alas, I've always been a sucker for audacity, and I am the sort of person who couldn't resist trying to top the entire... but never mind, you can see for yourself.
Click on to read my latest story and first fanfiction, a Vernor Vinge x Greg Egan crackfic.