Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Sweet Home 3D - Sweet Home 3D is a free interior design application that helps to draw the plan of house, arrange furniture on it and visit the results in 3D.
MakeHuman - MakeHuman is a free, open source, interactive modeling tool for creating custom 3D human characters.
SketchUp - 3D for Everyone
Bforartists - Bforartists is a fork of Blender.
MagicPlan - The floor plan creation app magicplan lets you create dimensioned floor plans without actively measuring or drawing. With its Augmented Reality.