Just in print (I have tons of systems in PDF):
Numenera
Cypher System
The One Ring (1e, 2e)
Twilight:2000 (4e)
AD&D (1e, 2e)
D&D (3.5, 5e)
Kromore
A Song of Ice & Fire
Invisible Sun
Pathfinder (1e, 2e)
Wheel of Time
Fate Core
Adventures in Middle-Earth
Lord of the Rings Roleplaying
13th Age...