Directories of colleges and universities and perhaps of particular departments or programs. Many sites will actually belong in another "directories" category within the ODP, for example a directory of physics departments may be better placed in Science/Physics.
All fee services (sites which provide the majority of its services for a fee or whose primary business is selling material on how to obtain aid) should be placed in the Fee Services category.
Program-specific submissions should go into more specific categories (e.g. medical programs should go into Medical Schools..)