The Leonids are reaching their peak tonight. This annual meteor shower peaks every time the Earth moves through the remnants of the comet Tempel-Tuttle. The meteor shower peaks when the Earth is directly intersecting the remnant streams ("filaments") from previous passes of the comet, and the peak for this year will be during the day of November 17th - unfortunate for those of us in the Western Hemisphere, but good for the night side of Earth at that time (primarily Asia).
Don't despair, however, as both the nights of Nov 16-17 and Nov 17-18 should provide some good meteor viewing even here in San Francisco. The Leonids appear to originate from the constellation Leo which rises in the east after midnight. As with all meteor showers, viewing gets better late at night into the early morning. Dress warmly and try to see a few. I'll be out early tomorrow to see what I can see.