We added a new software isGrafLab (Irregular Surface GRAvity Field LABoratory), which is a modified version of GrafLab. isGrafLab is capable to perform fast (it uses accelerated routines) and yet sufficiently accurate spherical harmonic synthesis on dense grids at irregular surfaces (e.g. the Earth surface). Any comments, criticism or queries will be appreciated. Feel free to write us. The emails can be found e.g. in the article or in the source code.