Links to 223 Free Modules/Adventures (DF and Others)
A fellow who goes by the handle of Landifarne has been compiling a list of modules for AD&D and for other TSR-era D&D games, and their more modern open-source successors. He started the list in March 2013 and has been keeping it updated as he learns of new modules. I believe it started out as a list of Dragonsfoot AD&D modules — which by itself is currently a list of 69 modules.
But he’s been growing it, so the list is now 224! There are a few that are not directly AD&D compatible, such as a few for Savage Worlds, but by large the list is AD&D compatible.
Sources span a gamut, including & Magazine and our stand-alone modules. The first post in this thread contains the list — he keeps updating it. You can find this thread here.
If anyone knows of any modules not in the list, feel free to let him know!