The first application that came to mind for me was the idea of creating your own spells out of various fundamental elements- the game could then procedurally generate the graphics for said spells based on their mechanical effects. Experienced players could intuitively "read" someone else's spell as it was being cast, knowing at a glance approximately what it would do.
The second application that comes to mind is a game that tweaks graphical elements in response to the same sort of subtle factors that earlier Silent Hill games tracked to gauge the protagonist's mental state, and by extension the ending they got. Here's a quick example off GameFAQs:
Requirements for "Leave" ending:
Do...
- Listen to the entire hallway conversation
- Examine Marys picture and letter occasionally
- Heal immediately after being hurt
- Excede maximum health limit
Do Not...
- Do not try to return to the apartment
- Do not stay close to Maria
In fact, procedural graphics would (hypothetically) allow a game or notgame to explore the core premise of
Divers (one of my major personal projects) in a very effective manner, especially if the procedural variables were maintained in a persistent multiplayer fashion. The central supernatural mechanism here is that the "Depths" (a side of our world we don't normally see, perceived as your surroundings gradually transforming into an abstract representation of their 'true character') are given form by the experiences human beings have in those locations. Procedural mechanics could track that- they could even record some of the most dramatic and/or common events, constructing "echoes" that become archetypical reflections of common trends.
Sorry, guess I'm rambling on- not to mention skimming over all the hard details. Hope the above at least makes a little sense.