Thanks to the film Gravity the Kessler syndrome is getting plenty of discussion at the moment. That's the idea that objects colliding in orbit could trigger a cascade, with the mass of debris produced potentially rendering spaceflight very hazardous, keeping us on the ground, grounded.
It's easy to imagine it used as a weapon, but for sci-fi and fantasy it could make for a strange new world - one not so far from the world we're in now.