This is absolutely the best *free* room planning/layout software I've ever come across. It's just a sluggish Flash app, but it works well, offers exceptional versatility, and with the free account you can plan up to a three floor house, stairs and all. You can even use it to plan a garden or a big event.
Create floor plans, house plans and home plans online with Floorplanner.com
Made laying my new apartment out (moving in a month) exceptionally easy!
Plan from apartment complex:
Translated into FloorPlanner, makes a very professional result:
Wirelessly posted (A Destroyer of short people: Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_3_1 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8G4 Safari/6533.18.5)
Very useful. Thanks dude!