Roomtodo - Simple yet powerful online tool for interior design and floorplans with built in walkthrough module.
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.
Planner 5D - Home Design Software & Interior Design Tool ONLINE for home & floor plans in 2D & 3D. Read more about Planner 5D.
Palette CAD - Palette CAD is one of the easiest 3D design software for those people who want to use a simple to use program for interior designs.
SketchUp - 3D for Everyone
InnoPlanner - InnoPlanner is a commercial based interior designing software.