The Guardian and the BBC News. CNN also has some videos and image galleries on the topic. But those resources are fairly basic. I went to NASA's website to see what they had to help students learn about asteroids and meteorites. Asteroid 2012 DA14 is due to fly by Earth today. NASA has some simulation images and video clips about 2012 DA14 here.
Killer Asteroids: Science Fiction or Science Fact is a NASA sponsored site for students. On Killer Asteroids students can learn where asteroids and comets come from, their structures, and the odds of a large asteroid hitting the Earth. Killer Asteroids offers a simulation that you can use to see the potential impact of various sizes of asteroids if they were to hit the Earth. Students can also try their hands at moving asteroids off course in a couple of games on the Killer Asteroids site.
Asteroid Mappers is another NASA supported site on which you can learn about asteroids. Asteroid Mappers gives students access to high resolution imagery of the giant asteroid named Vesta. The site asks visitors to help map the asteroid which will in turn help scientists determine the age and composition of Vesta.