We ran across this idea for creating a new floorplan and got a kick out of it. It's pretty old school, but tactile and immediate and it means less time in front of the computer. But also, we would have to make all that stuff by hand and we're a little bit lazy. So, if you've been wanting to rearrange your layout but want to see a preview before you go pushing things all around, jump below for a roundup of some great online tools to help you (and they're all free!).
Google Sketchup let's you get as into a design as you want. You can do a basic layout or you can go whole hog and design an entire room with paint colors and everything.
Arrange a Room from Better Homes and Gardens is our go-to for a quick look at a new layout. It's simple but you can't do much more than see shapes and a room.
My Virtual Home
Smart Draw
Design my Room from Point Click Home
Floorplanner
Image from Jack's Think Big
Before & After: Emily Henderson Transforms a Senior's Studio Space
Monica & Austin's Charming Bungalow
Good Food to Share 
The Big Book of Small, Cool Spaces 
Apartment Therapy Presents 
The Eight-Step Home Cure 
Ercol Bar Stool
How To Cook Fluffy, Tasty Quinoa
True Greek Recipe: Paximadi Bread Salad with Tomatoes, Feta and Capers
I've used www.3dream.net, which allowed me to draft floorplans that it changed into 3D customizable views - I can change the wall & floor colours & patterns, pick from thousands of 3D furniture images, move around the views.
Oh AT you always know what I want (and need) exactly when I need it. Thanks!
Also, www.icovia.com
I'm partial to the www.floorplanner.com one - it just got sucky once they kept limiting down free accounts. Wouldn't be so bad if they didn't want more than a few dollars for it but I guess everywhere wants to be rich.
i've tried to understand google sketchup, i swear! but i feel like the biggest numbskull when attempting to use it. and i'm more computer literate than average! ha!
i used to use intellidraw - it was a fast and easy program. but that was in the early days. i can't wait to plan my next project on these other programs... i must agree with kdkaboom - i'm computer literate as well but google sketchup is sketchy at best!
google sketch-up rocks my world! It's basically a free and somewhat more user friendly version of CAD. Just watch the video tutorials online, http://sketchup.google.com/training/videos.html. Also it helps to have a multi button mouse and be into using keyboard shortcuts. Of course if you just want to do a floor plan it may be a bit much since it's really meant for modeling in 3d (of course that can give you a better sense what a rearrangement of your space might actually look like). Plus there are loads of free models online including interior furnishings that you can just plop into the footprint of the room you're redesigning. (http://sketchup.google.com/3dwarehouse/) Believe it or not I don't work for them, I'm just a big fan.
anyone have any experience with these, or any other programs out there, to know about one that allows you to modify the wall/ceiling slants? our house has lots of unique ones in the upstairs (think barn or attic type shaped room), and i haven't been able to find one that works...
I checked out SmartPlanner - it looks like easy floorplan software with lots of templates, but it only works on a PC- not Mac-compatible. Grrr.