University of Michigan
Bio Kids: Critter Catalog: Mites
Ticks are really a type of mite, so this page refers to these arachnids as mites. Common questions about mites are answered, including classification information. The page also has photographs of mites and links to more in-depth...
University of California
Ucmp: Acari
This site from the University of California, Berkeley provides an introduction to the Acari, which include ticks and mites. Includes general information and pictures.