I experience a few different kinds of writer's block. One type is when I absolutely can't think of anything to say. The second is when I know what comes next in my story, but I can't think of a transition to get me from where I currently am in the story line to where I want it to end up. The third occurs when I am just tired of writing. For the first and second blocks, I try a change of scenery (I go for a walk or even just go to a different room), doing something else for a little while, or listening to music. For the third type of block I've found that writing sprints work really well for me. I set aside 30-45 minutes to write, write as much as I can in that time and then I take a break.