For a living, I work with a CAD (computer aid drafting) system. I use a very nice 3d system called Pro-Engineer at work. After I learned Pro-E, (and became pretty much awesome with it) it literally became part of how I think. Kind of like how reading and writing become part of you after you become literate. Or how it's pointless to ask a martial artist to fight without 'using any of that karate stuff'. It's now part of how I consider and evaluate new ideas. Its cool.
I've wanted some sort of CAD system for home for a while- it doesn't have to be as nice as Pro-e. A working 2-d system would suffice. But I didn't have one, so I was wistful for a while.
Then I decided to try to use MS Excel:
This is a screen shot of the layout I did when Liz and I redid our front walk. I reset the row height and column widths in XL to make squares in stead of the traditional rectangles, and then I zoomed way the heck out, decided my scale was one cell = 2" x 2" and started merging cells to represent the size blocks we were thinking about using. Copy, paste, etc. Tried out various patterns to see what stuff would look like, to see what would fill the space up best.
Here's a shot of the final, real world result:
Here's something I did the other day while bored:
It's a floor plan for an ultra miniature, one person house. Kind of a super efficient design with a single, college student type person in mind. It's dimensions are only 15x15 (tiny) but it has what you need. I lived in a place like this while I was missionarying in Nevada a million years ago. Me and Snave. Good times.
XL as a CAD system obviously has its drawbacks, but it is basically free and dimensionally accurate. Also, it's actaully alot simpler to use than Pro-E. It's basically just really really really nice graph paper. The commercial 3d systems out there are a million times awesomer than this, but people have been designing and building stuff successfully for thousands of years with basic 2-d drafting. Any drafter in the 60s and 70s would have loved to have had a CAD system as slick and sophisticated as XL is, once you are thinking out of the box enough to try to use it as one.