Time Travel
The idea I'm currently toying with is to make use of the Wings of the Valkyrie supplement, with some heavy modification.
Specifically I plan on having the players present at a demonstration of some new technology (Which for reasons I haven't fully fleshed out yet the researchers don't know isn't a time machine device, thinking maybe alien tech or something). Just as the demonstration commences, refugees from the future arrive begging the players for asylum. Moments later an alien/military shockforce arrive, hijinks ensue and Big Brawl A breaks out.
During the brawl, some of the supposed refugees flee further back into time, wind up killing Hitler and changing the present day drastically. I can already see how killing Hitler would make for some drastic historical changes (IE: Germany wins WW2 because they take longer to start it, thus developing jet engines and nuclear power first, America and Russia never have the cold war, etc etc etc).
Anyhow, it's about here that I plan on throwing Wings of the Valkyrie at the players. Or some derivative thereof. I still want to check with the players to make sure they're willing to have a game dealing with such subjects (I mean, c'mon, saving Hitler? That's really mean....).
P.S. Heya Ghost, seen you bouncing around. Yeah I have a FREd version of Red Eagle if you want to update him, but I'm playing him in a local f2f game, with him just starting out his career. Same kooky loony bin that he was though.