I may be missing it, but the cool thing about self-quantification usually is that you're not responsible for data acquisition. Things like Fitbit/Aria and Mint give you some automation and make it easier and more fun to track data (and ostensibly turn it into action).<p>Of course, there's no smart tape that I know of, but I think it would be CV-trivial to rescale & superimpose silhouettes of progressive pictures on top of each other to track progress. I know a lot of people would shy away from doing something like that, but it would be pretty cool. As it is, measurement with a tape is a pain and worse, subject to a good deal of human error.