I also picked up Robin's Laws of Good Game MasteringThis little book is a canon work for game mastering. Long-time gamemaster will read it and think, "wow, I knew that, but Robin says it so well and concisely!" For new gamemasters, you'll find the advice in this book enlightening, rewarding, and game-saving. For old pros, a little of that, but some great reminders waring about the traps of lazy gamemastering that even the best GM can trip from time to time, and some great exercises on how to succeeding at Search and Disable Device checks before hitting the next one.