Oregon State University
Osu: Volcano World: Spreading Plate Boundaries
This page has pictures and descriptions of different areas on Earth where the plates are spreading. Also includes links to more information on slow, medium, and fast moving plates.
US Geological Survey
U.s. Geological Survey: Quick Reference for Volcano Types
Succinct descriptions of the different kinds of volcanoes, with additional links for each.
Science Struck
Science Struck: Underwater Volcano Facts
Provides information about underwater volcanoes.