If you had your career as a GM to start again, what book would you wish to have read before you started on the path of learning to be a GM.
This needn't be restricted to RPG source and rulebooks of course.
It's head and shoulders over anything else related to the topic I've ever read in my life. Laws is a master. He also has a blog here.
Miles after that, subscription (for free) to Roleplaying Tips is recommended.
Also, read non-fiction books. History, economy and sociology are the most helpful topics that come to mind.
Play Unsafe. This book helped me get through my GM burnout and learn to have fun playing again.
It's a book about applying principles from improvisational theatre techniques to game mastering. It is specifically dedicated to reducing GM stress and increasing GM fun, all while creating a personalized, reactive, and fun game for players.
The First Edition AD&D Dungeon Master's Guide. Yes it's a rambling mess of disorganized thoughts in Gary's purple prose. It is also a treasure trove of ideas and inspiration. I've used it in Traveller and Villians & Vigilantes which is probably about as far afield as you can go.
For those insistent on world building The Shaping of Middle Earth is a great text. It shows the development of Middle Earth in multiple dimensions along with extensive notes.
Robin's Laws of Good Gamemastering has already been mentioned.
Of late I've been impressed with a lot of the material in D&D4's Dungeon Master's Guide 2.
For an example module with plenty of GM's advice, James Raggi's just released Tower of the Stargazer has replaced other new player modules in my mind.
These days, I would tell every wannabe GM to read the rules to the indie RPG Fiasco. Why? Because this is an engaging game that doesn't need a game master, doesn't need dice to resolve conflicts, and yet provides clear story structure.
I'm not saying other games don't need or benefit from these things, but it's a bit humbling to realize the labyrinths that we create to get lost in. Maybe some of those things are unnecessary.
Perhaps a painfully-obvious answer (my apologies):
Sets the still un-matched (in my opinion) standard for depth and richness of setting, strength of theme, weight of historical tone, and scale of action. If that doesn't encourage you to work harder to give your players a richer experience with thematic cohesion, structural and dramatic unity, and epic-scale conflicts set beside human frailties, I don't know what might.
Right now, I would say the book that has taught me the most about GMing is Apocalypse World by Vincent Baker, because it has the clearest and most explicit procedures for running the game that I have ever seen (not any game, this specific game). I really wish other games were as explicit about what the GM is supposed to do at any given moment as Apocalypse World is.
Reading that game has taught me:
- how to do the stuff I already knew how to do more consistently
- how to do things intentionally instead of just instictively
- how to talk explicitly about different things GMs are required to do for different games
I am optimistic that The Adventure Burner by Luke Crane will also be super useful, but I haven't had the chance to really dig into it yet.
Any of these would be a good one to read.
Basically decent book on writing (and not just genre writing) would be, in my opinion, an essential book for GMs.
Writing is not GMing, true and GMing is not writing. The techniques of writing, however, can be invaluable to GMs. I view role-playing games' relationship to written fiction in about the same way that I view the relationship between a jazz quartet and a classical chamber quartet.
Jazz's dynamics are very different from a chamber group's dynamics, but a chamber group's technique and technical skills are fully applicable to much of what a jazz quartet does. In the same vein, many of the techniques and technical skills of a writer can be adapted (or lifted outright) for the use of a good GM (and even player).
For RPG reading it's a three way tie between Play Dirty by John Wick, Robin's Laws of Good Game Mastering by Robin D Laws, and the XDM by Tracy Hickman. Between the three you get a very solid foundation of what makes a good GM, what to look for, and what to work for when running your game. Wick can come across a bit arrogant at times, but the anecdotes are solid examples. Hickman comes across a bit too silly at times, but the message is still good, and Robin hits a solid middle ground between the two.
Aside from that, it would depend on the genre. I don't think Tolkien is required reading for Fantasy, but you should have read some fantasy if you want to run a game in that genre. The same for sci-fi, crime, and everything else. Exposure to the genre helps you with the themes and the running of it.]
I would recommand The Art Of Game Design as it speaks about any kind of games. Almost everything in this book is valid to understand that as a game master your creating an experience for your players.
I'd recommend Orson Scott Card's "Characters & Viewpoint" (especially the first half of the book) and Lajos Egri's "The Art of Dramatic Writing". These handbooks were written for writers primarily, but a GM/referee/storyteller/etc may profit from them immensely as well - they sum up the basic and most fundamental tricks of creating memorable, dynamic and full characters, engaging conflicts and storylines. Anyone who understands (let alone masters) these will not be lost as a beginner storyteller (if they have some social skills as well, of course.) Monsters, magic and world-building come, imo, definitely after these - for there's a story without an orc wizard but an orc wizard isn't too interesting without a story. :)
My two cents only, though. :)
There are two books that I feel very confident in recommending to any and all GMs -- Star Trek TOS Narrator's Kit and The Risus Companion, both by S. John Ross. Don't let the Star Trek and Risus connections convince you that these are anything but solid, well-written, very handy and very user-friendly guides to good gamemastering for anyone running any game -- novice and veteran alike.
Adding into some of the "find good books about writing," I've found Vonnegut's Eight Rules for Writing to be very helpful, as long as you read them as good suggestions, rather than dogmatic rules and remember, as the first commenter at the link does, that you can break all of them except for the first one.
The Sword of truth series by Terry Goodkind. Especially if you plan on having large scale combats and would like to describe your spells well. In general I find if I am going to be DM in a certain main stream world reading one of the more popular or latest books will make your understanding of how things are supposed to work there. And of course the book that got me into DMing, dnd in general Dragonlance Chronicles the mention spell components, all the limits and benefits pcs can have, think it came from authors sessions.