There are two kinds of writer's block: 1) Hitting a wall when you're trying to finish a current work (e.g., unsure as to how to fill a plot hole that you didn't previously consider) and 2) Hitting a wall when you're trying to start a new work. For the first case, I take a 20-minute nap in complete darkness. It's just enough time to fall into a slightly deeper sleep - one can recognize it when you start to have some freaky dreams that you're still consciously aware of. Most of the time, that works. If it doesn't then I work on a different section. For the second case, I pass ideas to people I trust. More specifically, I give them loglines to gauge their receptiveness. If the logline works then I give them the pitch. If that works, then I give them an impromptu jacket copy. Finally, if that works then I give them a synopsis. This may sound lengthy, but there's rarely a greater sense of regret towards when you're deep into a work and you realize that there's not much substance to it. By the way, if you're looking for an agent/editor/publisher, you will need to do these steps anyway.