In what may be either a class project or the weirdest case of semi-plagiarism in the blogosphere there are several new blogs which give examples and definitions of various types of maps. Map Catalog, Matt Mudano's Map Blog, The World of Maps, and Maps Galore all have fifty some examples of various types of maps. Planimetric, Cadastral, Choropleth, Dot Distribution, and more shown and described. The definitions are short but it does a good job making the map type easily understood.
If you need to know what a certain map type is then the above blogs are a descent place to start.