It would be useful to have a settings.xml file next to the project pom that could contain project specific settings. For example, when switching between projects it is sometimes necessary to also change the location of the local repository, or use a different set of repositories and/or mirror settings for each project.
If a settings.xml file could be included with a project checkout, then the repositories needed for the build could be included (instead of putting them in the pom) along with any other project specific settings.
The tricky part is intelligently handling multi-module projects. For a multi-module project I don't want to include a separate settings.xml file for each directory. So Maven could recursively check each parent directory until it either (1) finds a settings.xml, (2) finds a directory with no pom.xml, or (3) finds the root directory.