I'm looking for ways for Minecraft worlds to be explored in creative mode (i.e. allows flying), but does not allow the world to be modified in any way. Is there an application that allows this, or a mode that the game can be run in? I looked in the profile properties and didn't see anything there. While searching online, it sounds like I might need to run something like CraftBukkit and then set properties on the server, but I was hoping there was an easy button for this.
The current snapshots for 1.8 allow this with a "spectator" game mode. Spectators are always flying, and clip through blocks. As a consequence of this, they also can't land like you would in creative, and will simply clip through to the void if they try. Spectators can also view the world through the eyes of a player or mob, as well as view, but not modify the contents of chests, dispensers, etc.
Of course, being a spectator also means that regular (i.e. survival and adventure mode) players won't be able to see you, and you only appear as a disembodied head to other spectators, but the other features it offers may be worth that cost.