Cura - Cura aims to be a end solution for personal 3D printing with RepRap based machines.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Slic3r - STL-to-GCODE translator for RepRap printers Here comes Slic3r! Its features are: - speed
Sculptris - Sculptris: Enter a world of digital art without barriers.
Repetier - Software for controlling RepRap style 3D-printer like Mendel, Darwin or Prusa mendel.
meshmixer - meshmixer is an experimental 3D modeling tool for making 3D mashups without too much hassle.