Heroes and Hardships
Earl of Fife's original d10 dice pool system.
Other RPGs
Adventures for many great RPGs, including Demo Gate, Against the Darkmaster, etc.
Mothership
Adventures for Mothership RPG.
OSR
OSR adventures for Old-School Essentials and MORK BORG.
Mythras
Mythras and Basic RolePlaying adventures.
d20 OGL
d20 OGL adventures, for 13th Age, 5E, Starfinder, and more.
Stars Without Number
Stars Without Number adventures.