One of the terms that's come up lately in gaming circles is the concept of the "Sandbox." As I understand it, the term originated in console games, particularly with the Grand Theft Auto series, where your character could pretty much have all manner of adventures by just walking around and interacting with the environment. In tabletop gaming, the term has come to mean a setting with all the basic pieces of good adventures, but no strong overarching plotlines that must be stringently observed. It works well for a certain style of fantasy gaming (notably the more "old school" approaches to the genre) and quite well for spacefaring science fiction. To me, the underlying principle is that the world is there for the player to discover. Not to read about in some manual somewhere or have the GM recite as part of a six hundred page background document.
This is where I feel most published (and many home-grown) superhero settings fall down rather badly. Even the ones I love are filled to the brim with cool places that are already found, cool people who are already known, and cool stuff that happened twenty years ago. In short, tons of wasted potential. Sure, they provide future story hooks, but where's the joy of discovery? Where's the novelty? Where's the sense that the GM isn't just taking the players on a guided tour of the setting?
For my current Champions campaign, I'm trying to avoid that. Yes, I'm using bits and pieces from a number of published settings, but I'm largely ignoring any background material that doesn't suit my immediate needs.
Apart from freeing me from continuity I don't particularly care for, it's also allowed me to be a good deal more free-wheeling in my approach and preparations. After the events of last session, I really had no idea of what was going on beyond the immediate crimes the heroes encountered. Since then, I've been pulling out bits and pieces to see what will fit and whatever sticks is what I'll use. But the truth is, there are still two or three possible scenarios that could play out at the moment and which one I use will ultimately be in the players' hands. In the past, I would have been more inclined to move the story in a single direction (some ungenerous souls might call this "railroading" -- they might be correct). At present, I'm feeling much more comfortable in sitting back and letting them tell me where they want to go and adjust the story to their plans.
Given that I've always seen supers as a largely "reactive" genre (where the PCs have to react to events of the world around them), this is a bit of a reversal for me. I'm interested in seeing where it goes.