Many times when I'm writing a trick/trap article I will take either a specific trap from one of these works, or a specific theme in general (such as elevators). Then I do research through a variety of sources (re: Books and the Internet) to determine aspects of the trap, how it might work, and ways to preserve agency. Also, I use my own brain.
Here is a listing of the various sources that I use. Links present where available.
Google Image Search
Grimtooth's Traps (Trademark of Flying Buffalo Inc.)
Grimtooth's Traps Too (Trademark of Flying Buffalo Inc.)
Grimtooth's Traps Fore (Trademark of Flying Buffalo Inc.)
Grimtooth's Traps Ate! (Trademark of Flying Buffalo Inc.)
Mantrapping by Ragnar Benson
Undermountain Boxed Set
Dungeons by AEG
World Builder by Gary Gygax
Traps and Treachery I By Fantasy Flight Games
Traps and Treachery II by Fantasy Flight Games
Dungeon Craft by Fantasy Flight Games
Goods and Gear, the Ultimate Adventurer's Guide by Kenzer & Co.
(I have several other equipment guides, but I believe the above is the only one I've used as reference for the trap series)
Ultimate Toolbox by AEG
Dragon Magazine (Various, 300+ issues) by (Various)
Fight On! (Various, 12 Issues) by (Various)
Knockspell (Various, 3 issues) by (Various)
Various Arduin Books
Dungeon Master's Guide by Gary Gygax
Dungeon Master's Guide 3rd edition
Pathfinder Core Rulebook
Pathfinder Reference Document Online
Dungeon Builders Guidebook
Dungeoneers Survival Guide 1st Edition by Douglas Niles
Dungeonscape by Jason Bulmahn and Rich Burlew
Stronghold Builders Guidebook by Matt Forbeck and David Noonan
Netbook of Traps (2001)
EN World (Various)
Locks & Traps (source defunct)
Other various internet sources
I've also got about 140 modules that I've perused for trap ideas - I will be glad to go through and find the module reference for any specific trap, but rest assured, I have also consulted them as references for ideas. There are likely unlisted research sources that escape me at the moment.
Let me tell you, there is little that is truly original in the world. Origins of many of these ideas are older then the last book you saw them printed in. I figured a fairly comprehensive listing would be helpful in elucidating that though the discussion of agency is my creation, traps and their various incarnations have a wide variety of sources in gaming and throughout history.
I attempt to at least know the attribution of each picture or article I post on this blog, as any cursory review by a non-myopic reader will tell you. If you know the attribution of a picture I don't have labeled or have a question about sources of an article, e-mail me and I will add the attribution. If you just want to point out that there are unattributed pictures on this blog, then I don't recommend you visit any tumblr streams.