I just discovered an iPhone app named My Measures & Dimensions that lets you take any photo and quickly draw dimensions on top of objects or spaces in the photo. Typically, I use a piece of scrap paper for this, and end up forgetting to bring it with me when I need it. After photos are marked up with measurements, they can be emailed to anyone, or added to the iPhone’s photo library.
So far, this app seems incredibly useful for several purposes. I’m using it to quickly record the measurements of rooms in our house. It’s also handy to note the dimensions of some bookshelves in our daughter’s room, so we’ll know what can fit inside. I can easily imagine several other uses too. Here’s a direct link to My Measures in the iTunes Store.