I don't know of an app tht would do it, but I think it's a great idea. We have developers in the development section who are looking for inspirations. Put the idea up there and see if anyone's interested in writing such an app. (It would give you a signature box, then capture the time, date and a picture of the signature and save it to the destination you chose in Settings. (Maybe even write the EXIF time, date and location to the file.) And, of course, it would have to work on the SD card with Kit Kat.