The following sites have good, reliable information for starting almost any research project:
 

Kids InfoBits




National Geographic                                                                                          
http://www.nationalgeographic.org

The History Channel
http://www.history.com/

Smithsonian
http://www.si.edu/

Franklin Institute
http://www2.fi.edu/

Biography
http://www.biography.com/

How Stuff Works
http://www.howstuffworks.com/

NASA
http://www.nasa.gov/

The American Library Association's Great Web Sites for Kids
http://gws.ala.org/