The Mollweide projection is and equal area projection, pseudocylindrical.
The Mollweide Projection was invented by Astronomer Karl Brandon Mollweide of Leipzig (1774 - 1825) in 1805. The projection is commonly used by astronomers for projectiong the celestial sphere. This is the projection used by the WMAP for the Cosmic Background Radiation.
Other names for this projection: Hammer-Aitoff, Aitoff, Homolographic, and Babinet
I'm thinking about adding some information about the mathematics, and simplify it for non math geeks, and programmers. (I recommend using the PROJ4 library)