NASA
Nasa: Latest Conclusions of the Comet Collision
This site from NASA allows one to read the reports by scientists of what we learned from observing the giant collision of Comet Shoemaker-Levy 9 with Jupiter. Some are very technical, others for general audiences.
NASA
Nasa: Top 20 Comet Shoemaker Levy Images
This site from the National Aeronautics and Space Administration provides the most popular images at the JPL Comet Shoemaker-Levy home page during the month of July 1994, when the comet was impacting Jupiter.
Space Telescope Science Institute
Hubblesite: Observations Shed Light on Jupiter Collision
This site from Hubblesite of the National Aeronautics and Space Administration provides basic information and photographs of the collision of Comet Shoemaker-Levy 9 with Jupiter. A good site to check out on the subject.