May not work for everyone, but seems to help me. When I'm not sure where my story is going and can't quite get anything on the page I hold a word war with myself. I don't usually try to write anything about the story itself, rather I concentrate on describing the place my character is in right then, or giving more background on that character or their family.
I don't time myself, just head the section ***Word war*** so I can find it easily later and start typing as fast and furiously as I can. By marking it as a word war I can easily take a look at it later and stick it in a more appropriate place or take it out altogether.
After 'warming up' like that I can usually pick up the thread of my story and get back on track.
Anyone else have any good writing tips that I can steal, er, borrow?