I learned of of the MagicPlan App from the Photography For Real Estate (PFRE) blog.

According to PFRE:

"The app is free for download. The final floor plan is free for non-commercial use (includes a watermark) and $1.10 USD for commercial use (with the watermark removed)."

"Running this app takes some practice. It took me several rooms to get the hang of selecting the corners of the room even though you can’t see the exact corner of the room because of furniture or drapes etc. But once you get the hang of it, you can put together floor plans very quickly. This app makes it very easy to add floor plans as a product to your real estate photography services if you are inclined to do that."