I just learned via the Royal Observatory Greenwich blog that asteroid 2008 AF3 passed pretty close to the Earth last night -- 475,000 kilometers from us -- just outside the orbit of the Moon. It won't hit us, but it was a close enough shave to be somewhat interesting.
The asteroid was discovered on January 10, just three days ago, and has an elliptical orbit that maxes out at the orbit of Mars and brings it in to the Sun as close as Earth's own orbit. This pass is close enough to change its orbit, so I'll be interested in seeing what the orbit looks like after it swings by.
2008 AF3 is pretty faint (it's small, though I cannot find its actual size), and will only be viewable with biggish 'scopes -- at a max magnitude 14, it's less than one-thousandth as bright as the faintest star you can see with your naked eye. I expect there will be plenty of amateurs getting images of it, though. If you get any, post them to BAUT! A skymap of the flyby -- and for many other asteroids too -- is at Tom's Asteroid Flyby page, a very cool resource that I have now bookmarked.
Interestingly, Tom's page has it approaching a bit closer (380,000 km) than what's at the JPL page (475,000 km). I'm not sure which is correct, but both mean it was a clean miss.
We're getting another near miss at the end of the month, too. This is a good time to be an asteroid hunter!