Floorplanner - Floor plan interior design software. Design your house, home, room, apartment, kitchen, bathroom, bedroom, office or classroom online for free or sell real estate better with interactive 2D and 3D floorplans.
open3mod - A free, Open-Source 3D Viewer designed to make it all easier. Massive 3D Format support
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.
CtrlView - Fast, compact, powerful viewer/converter for different 2D/3D raster/vector file formats
SketchUp - 3D for Everyone
Blender - Blender is the open source, cross platform suite of tools for 3D creation.