List of possible classifiers and types in dependencies

From the Maven Reference:

Update

Oops, I misunderstood the question. Here is my second shot (important parts italicized by me):

The classifier allows to distinguish artifacts that were built from the same POM but differ in their content. It is some optional and arbitrary string that - if present - is appended to the artifact name just after the version number.

To me this suggests that you can use any classifier you want - it is not limited to a certain set of possible values.

type: Corresponds to the dependant artifact's packaging type. This defaults to jar. While it usually represents the extension on the filename of the dependency, that is not always the case. A type can be mapped to a different extension and a classifier. The type often corresponds to the packaging used, though this is also not always the case. Some examples are jar, ejb-client and test-jar. New types can be defined by plugins that set extensions to true, so this is not a complete list.

Which again tells, that although usually you won't find anything else in this property as the well known packaging types, the list of possible values is open and plugin-specific.