This may sound smart ass-ish, but it's true: I deal with writer's block by writing the next sentence. "But what if that sentence sucks?" you ask. Then I fix it. Dealing with writer's block, for me, is more a lack of discipline rather than a lack of something to say. Once you put something--anything, really--down on paper/screen/napkin, then that forward momentum usually leads to a paragraph, then a page, and then a book.