Wanted to start this thread because home design software can have some advantages over more general-use software. Namely, it tends to be far more automated. You can drag and drop doors and windows that snap right into walls seamlessly, and still re-size the wall without distorting the door/window. Everything is proportioned to real-world measurements. Furniture manufacturers have HUGE catalogs of there products available for these types of programs. Elements are generally saved as separate pieces, which makes it easy to create sub-props in 3DX.

Only a few of these programs actually output 3D models. Let's make a list!

http://www.sweethome3d.com/

This one can export OBJ files. It is free and open source.

http://pcon-planner.com/en/[url=http://pcon-planner.com/en/][/url]

Free version can save 3DS.