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.
Modelio - Modelio is an open source modeling tool supporting natively UML, BPMN and model exchange with XMI.
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.
Diagramo - Diagramo is an online flowchart software - diagrams (create, edit and share)
SketchUp - 3D for Everyone
UML Designer - UML Designer provides a set of common diagrams to work with UML 2.5 models.