Floorplanner.com THIS IS AWESOME! TOTALLY FREE! you can draw your own floor plans for your dream house, draw a room you want to re-model or re-decorate, plan a deck, a backyard, anything and it's free! Any size, any elements, this is great!
Autodesk® Homestyler®’s FREE* online home design software will bring your interior design ideas and remodeling dreams to life. Take the guesswork out of home remodeling projects by laying out floor plans with all the finishing touches such as doors, windows, furniture and colors. Design your dream home online!
Blender is a free 3-D software that lets you create whatever model you want. Its difficulty is based on how well you know the hot keys. I like to use this program a lot with Garry's Mod to see how well I can make body armor or some kind of car part. I spend most of my time learning more about blender and what I can do with it.