HELLAS: Quick Start Rules - Hellas is an exciting fusion of high drama, action-adventure, romance, mythology-infused space opera and science fiction - all that seems to be missing is the kitchen sink.
S.A.V.A.G.E. Essentials Rulebook - (Survival and Victory after Global Extinction) - Stripped down core rules for free. When the author says "for experienced gamers only", I lean toward beleiving him. Still, mightbe some stuff stealable for your Mutant Future game.
Promethean: The Created Demo - Promethean: The Created Promo - Think Frankenstein and Golems. Its set in White Wolf's World of Darkness. Hell, with of of the WoD quickstarts, you could game for months and not spend a cent.
SLA Industries FREE Rulebook - Not a quickstart, as the quickstart's link appears to be dead. Instead, its the full core rulebook. Spies, espionage, magic, biogenetics and more. Over 300 pages. Full game. 'Nuff said.