Here are some campaign concepts I would like to play, but have not gotten a chance to. More may come later and I may elaborate on one if there is interest.
Alfheim Wasteland: The elves once had a highly advanced technological society, before war split their race and resulted in the use of weapons of mass destruction. The elves' civilization was destroyed and most of their lands ravaged. Now ten millennia later the remnants of ancient ruins dot the wastelands, guarded by mechanical and mystical guardians. Techno-barbarian orc tribes rule much of the continent, though the remnants of the ancient elven empire hold fiercely on to the territory they retain. They have reached out to the great elven diaspora and their allies for help, promising them territory in exchange for their military services.
American Fairyland: It's Earth, but not as we know it. Two planes have collided, resulting in a fusion between the two, which resembles the world outside your window, but with magic and mythical creatures. Few remember the world as it was, with an entire history of magic having overridden our own. The culture remains fairly similar, only altered by the presence of magic. Creatures like dwarves, elves and orcs all have a place in this new world.
Guardian's Realm: A more "gonzo" setting, with inspiration taken from anime, Final Fantasy, Pokemon, etc. A deity has created their own demiplane and filled it with bits and pieces from other worlds. This deity resides at the top of a great tower, surrounding which is the principal city of the planet.
Star Wars: Destiny of the Republic: The players follow Jedi Master Qui-Gon Jinn on "damn-fool idealistic crusades," as the Galaxy falls into the chaos of the Clone Wars in an alternate universe. The Mandalorian Clan Wars rage, but a possibility of peace exists in the young Satine of Clan Kryze.Out of the Arkanian Civil War a galactic threat emerges, the lifeform known as Atha Prime, as well as Clone Masters who desire to gain profit from their now unused skills.