Map Projections used in the Stooke map collection:

Simple Cylindrical:  Each pixel in X and Y (sample and line) represents an
equal angular increment of latitude or longitude.  Also called Equirectangular
or Plat Carree.  Sometimes referred to (incorrectly) as Unprojected.

Azimuthal Equidistant: Azimuthal projection in which (on a sphere) equal
distances from the centre represent equal angular distances on a globe. 
If centered at the pole, all parallels of latitude will be equally spaced
concentric circles.  When extended to a non-spherical body the grid lines
become irregular but the principle is the same. 

Morphographic:  A term describing Azimuthal projections in which the
conventional radius constant (for a spherical map) is replaced by a variable,
the local radius at each projected point.  The radii are taken or interpolated
from a shape model. Every variety of Azimuthal projection can also be made
in a Morphographic version.  These projections are very useful for showing
locations of small features relative to the overall irregular shape.  However,
although they approximate characteristics such as equal area, equal 
distance or true shape, they do not retain those characteristics exactly. 
Note that Morphographic projections can be created using any shape model,
including the actual shape of a body, a best-fit or similar triaxial ellipsoid
representing the body, and the convex hull of the body.

Morphographic Equidistant:  Morphographic variety of the Azimuthal Equidistant 
projection.

Morphographic Equal Area:  Morphographic variety of Lambert's Azimuthal Equal
Area projection.

Morphographic Conformal:  Morphographic variety of the Azimuthal Conformal 
(Stereographic) projection.

Polar Azimuthal:  Azimuthal projection (of any variety) centered on a pole.

Bugaevsky's Conformal:  A Russian projection, rarely used, which adapts the
Mercator (Cylindrical Conformal) projection for a triaxial Ellipsoid. 
Attempts to create maps using grid coordinates provided by Lev Bugaevsky are
not successful because Bugaevsky used a non-planetocentric definition of
latitude.  The issue has not been resolved.

Prismographic:  An attempt by Stooke to resolve the problem in Bugaevsky's
projection.  It is a cylindrical projection in which X coordinates correspond
to the incremental distance from the prime meridian to that longitude measured
along the equator, and Y coordinates correspond to the incremental distance
from the equator to that latitude measured along the appropriate meridian. 
Neither Conformal nor Equal Area, but a good visual impression of an elongated
body.

(Descriptions provided by Phil Stooke, June 12, 2003.)

Note (added Aug. 2015) regarding ellipsoidal projections in version 3.0:

This PDS-SBN submission contains maps of several highly elongated objects. 
A standard procedure was followed to produce these maps.  The photomosaic
was projected onto a triaxial ellipsoid which was in turn projected into
Morphographic Equidistant projection maps of opposite 'hemispheres' (north
and south, or equatorial).  The Morphographic projection is an azimuthal
projection (in this case azimuthal equidistant) in which the radius constant
usually present in the projection equations is replaced with a variable, the
radius at any given point.  At the ends of an elongated object the radius is
larger, so those points are projected further from the origin and grid
spacing is enlarged.  The resulting map is often easier to interpret or
match with images than a sphere-derived cylindrical or azimuthal projection.
To simplify the mapping, since all these objects have very roughly the same
degree of elongation, a standard ellipsoid was used, with axes of 1.0, 0.4
and 0.4 km multiplied by the length of the long axis of the body.  More
precise results would be obtained using a distinct ellipsoid tailored for
each body, but there would be relatively little difference in these cases. 
Unlabelled 10 degree grids are added to some maps.  File names indicate 90
and 270 longitudes according to the convention in the control source papers
(east longitudes for Itokawa, Steins and Hartley 2, west for Ida, Eros and
Borrelly).  Steins is not greatly elongated, so ellipsoidal maps were not
made.