Being someone who has both programming skills and creative urges, I suppose it is not very surprising that I am very interested in procedural content. Code is a crucial element of interactivity, so I've always thought that using code to generate or modify content is an easy and fascinating way to make interactive entertainment richer, deeper, or just cuter.
This explains why I bought Texturing and Modeling: A Procedural Approach, and then sold it again to buy the second edition, even though I hadn't really implemented anything from it. (I'm now tempted by the third edition.) It also explains why I'm a fan of Ken Perlin's work.
And it explains why I'm a fan of generators, translators, and other cute little gadgets, such as:
There's too much to mention really. But I cannot leave out the
Random Jack Vance Dying Earth Quote Generator, even though it does not do a lot of generating. But first of all this role-playing game by Robin D. Laws is really well-designed, and second I'm a huge Jack Vance fan, and these quotes are some of the best examples of his delightful writing skills. (One may appear familiar to people contacting me per ICQ.)
I think all of these various gadgets and tricks can be used to create emotional effects in games. Obviously, some of them are gimmicks that are hard to use in a generic manner, but cool for occasional spot effects. Many of them are particularly useful with non-standard input and connectivity mechanisms. A game like Animal Crossing could particularly benefit from these tricks, if it doesn't do so already. These gadgets can also be useful to confuse the player, which can be a worthy goal if your game involves surrealism, psychological states, horror, or the uncanny. However, if you use player input to generate content, some care must be taken with the player's suspension of disbelief.
To conclude, I'll describe a concrete example of the use of procedural content from a project I worked on that never got finished. The player takes on the role of a fallen god, a once-powerful being revered by all, who now wakes up in a dusty tomb, severely weakened. The idea was to let the player enter his character's name at the beginning of the game, as is standard in many games. Then, towards the end of the first act, the player would discover a huge, crumbled statue of himself, with his own name carved into the weathered pedestal. We had TrueType to 3D mesh and 3D Boolean operation code lying around, so my hope was it would have taken about a week or so to implement. It's just a gimmick, but one that, if done well, might have an emotional impact somewhat like the ending of the original Planet of the Apes.
(Links from various sources, including the excellent BoingBoing.)