I myself (One of the lucky ones) have never suffered from writer's block, rather the ideas just won't stop. An example from a few years ago I've long since given up was ' Vampires + Robots + Dinosaurs' Don't ask me how it got to that. It started as a slightly altered present time with the edition of mythological creatures we've all seen it. Then it went into a Future-scape where Robots and genetic engineering was possible. Any tips on how to slow down or how to set something in stone?