[sgtcallistan]

Have run (but have no site to link to):

GURPS: WWII, Zha Rodina! (yes, I know it's spelt wrong): a Red Air Force cinematic-but-lethal WWII squadron of frontal aviation game. Ran for about 12 weeks, one night a week, some years ago. Went from the German invasion to the Crimea, time on fast-forward.

GURPS: The Box. A TL9 or so interplanetary State (totalitarian along Buearaucratic/Progressivist lines) discovers a teleport box on Mars. Characters are ordered to take interstellar beacons through, with colonists to follow later. No going back; you are what you bring with you. The ultimate escape for the oppressed, or the triumph of The State across the Stars? Based on a favourite SF short story of mine.
Played for about 10 weeks, one night a week, with some Sundays as well.

GURPS: Knights of the Star. Conflation of Star Wars Jedi, Dune politics and houses, animoid folks from Cordwainer Smith books. Rubber science, cinematic in the extreme, signature gear, script immunity for PCs.
A slow-burning campaign that has been revisited several times with various groups and players; has lasted over ten years now.

GURPS: Teen Muties. A 'school for gifted youth' collects or finds students who are taught to employ their gifts by teachers who were once heroes themselves. Outcasts, orphans or simply odd-looking; they exist in a world where all other comic characters exist or have existed (mostly UK-based ones).
Plots mined from all of comic book history. Other timelines and alternates, vistors from the future, 'the very last nazi giant robot of all', demons and angels, it's all happened.
Has been rebooted and revisited several times with different groups, resulting in a fourth-wall-breaky style that means characters and events are reworked and reinterpreted as time passes; while the time is an eternal present day.