Hi,
I'm trying to collect a list of 3E/d20 era products which bear relevance to Mystara.
WotC Books with Mystara TeasersMiniatures Handbook (Contains Catfolk race)
Lords of Madness (Rules useful for Brain Collectors, Chokers etc)
Epic Level Handbook (Stats for Brain Collector and Blackball)
Tome of Magic 3E. (Contains Vault of Catharandamus)
Fiendish Codex I: Hordes of the Abyss (Mentions Ulgurshek, a draeden)
Elder Evils (Contains info on Zargon)
Fiend Folio (Stats for Maelephant aka Malfera)
Book of Vile Darkness (Info on Demogorgon and Orcus)
Monster Manual I (Aranea, Aquatic Elf, Choker, Nightshade, Nalfeshnee, Roper etc)
Monster Manual II (Catoblepas, Frost Salamander, Gem Dragons, Hook Horror, Kopru, Skorpionfolk)
Deities and Demigods (Norse Pantheon, Pharaoic Pantheon etc)
Arms and Equipment Guide (Hippocampus)
Manual of the Planes (Orcus, Planes)
Planar Handbook (Limbo, Planes)
WotC Free DownloadsReturn to the Temple of the Frog
http://www.wizards.com/default.asp?x=dnd/oa/20070223aNight of the Straw Men
http://www.wizards.com/default.asp?x=dnd/duad/20080507Dragon Magazine Articles (Paizo)Dragon # 315 Hollow World, Red Steel, Blackmoor and Cynidicea
Dragon # 318 Children of Ka (Hollow World article)
Dragon # 323 Ecology of the Choker.
Dragon # 325 Winning Races: Lupins. Bringing Lupins into 3.5E.
Dragon # 327 Winning Races: Diaboli. Bringing Diaboli into 3.5E.
Dragon # 339 Dusanu, Nagpa and Phanaton.
Dragon # 343 Nuckalavee and Malfera.
Dragon # 344 VOYAGE OF THE PRINCESS ARK 36
Dungeon Magazine Articles (Paizo)Dungeon #114 (Isle of Dread)
Dungeon # 115 (Blackmoor)
Dungeon #139 (Savage Tide I)
Dungeon #140 (Savage Tide II)
Dungeon #141 (Savage Tide III)
Dungeon #142 (Cynicidea and Savage Tide IV)
Dungeon #143 (Savage Tide V)
Dungeon #144 (Savage Tide VI, Bargle the Infamous)
Dungeon #145 (Savage Tide VII)
Dungeon #146 (Savage Tide VIII)
Dungeon #147 (Savage Tide IX)
Dungeon #148 (Savage Tide X)
Dungeon #149 (Savage Tide XI)
Dungeon #150 (Savage Tide XII, Kill Bargle)
Zeitgeist GamesDave Arneson's Blackmoor D20 (D&D 3.5 Edition)
The Redwood Scar (D&D 3.5 Edition)
The Wizard's Cabal (D&D 3.5 Edition)
The Dungeons of Castle Blackmoor
Dave Arneson's Blackmoor D&D 3.5 Softcover
Player's Guide to Blackmoor
Temple of the Frog (D&D 3.5 Edition)
Clock and Steam (D&D 3.5 Edition)
Riders of Hak (D&D 3.5 Edition)
City of the Gods (D&D 3.5 Edition)
Anything missing?

Havard