Edheldur said:
Campaign Sourcebook and Catacomb Guide
Castle Guide, The
Creative Campaigning
The 1E hardbacks are of limited utility to a 3E gamer (some of them, like the WSG, are of limited utility to a 1E gamer, IMO). The 2E guides, above, could be handy, though. The material in them is not very crunch-oriented (there's some, but it isn't the purpose of the books), and could be easily applied to a 3E game.
However, I'd recommend you take a look at the
Gygaxian Fantasy Worlds line of books. The ones I've purchased have been very good. Like the 2E guidebooks, they're more resources/guides, rather than crunch, but the crunch that *is* included is presented in both Lejendary Adventure and d20 system versions. These books surprised me, because when I read about them, I thought "Hmm. Nice, but I don't really need them..." However, once I purchased them I found them to be oft-referenced and valuable additions to my gaming library. The three that I have are:
World Builder - this is a book of lists. Take the section from the 1E DMG that presents all the lists of rooms, colors, gems, dungeon dressing, etc., and expand it to a full length book. This one was the biggest surprise; since I bought it, I've used it for every preparation session, and sometimes even in play.
Living Fantasy - this is a book that presents a look at a fantasy society, covering settlement patterns, social classes, economics, crime & punishment, impact of magic, et cetera.
Insidiae - a "brainstormers guide to adventure writing." This one bears some similarities to the
World Builders Guidebook or the
Adventure Cookbook. It's that type of book. (My Latin is sadly limited, but I believe the title is intended to refer to "plots," although I think "insidiae" has more of an "ambush" or "trap/trick" connotation, rather than a "storyline" connotation. I could be wrong, though...)
