Tales of the Grotesque and Dungeonesque offers a Gothic Fantasy Adventure Generator, which produces sentences for adventure seeds.
Morgalad is a fantasy RPG set in a pre-medieval world. You can download the starter set for free.
For GURPS players, here is an online automated treasure generator.
Cybercity Blues is a free RPG that has a lighter take on the cyberpunk genre. The authors write:
“Cyberblues is a bit like Cyberpunk, only more mellow.”
Cyberblues City is a near-future, action-adventure roleplaying game. Fast-playing and often funny, it offers a lighter take on the cyberpunk genre, both in terms of system and tone. Cyberblues City uses a much modified version of the Fudge roleplaying system designed to make it easy on GMs. And best of all, it is absolutely free.
Legends of Time and Space is a free role playing game that takes its inspiration from Steve Jackson Games’ The Fantasy Trip.