You've got to see the Random Story Generator. It's a kick.
Another nifty tool is yWriter, a free "novel writing software" utility, that helps organize, strategize, and plan your novel.
yWriter has a handy word counter that helps you see how much you've written and how much you have left until you hit your goal. It also organizes your scenes in easily movable chunks, which helps you edit your book with ease.
Here's another one. Check out FreeMind as a general brainstorming tool. FreeMind is a freeware mind-mapping software that some novelists have found useful for creating timelines, mapping cause-and-effect between multiple entities in stories (like various military groups in a war), and general brainstorming.
Be sure to head over to the World Builders page for more awesome idea starters.