There is a free light meter app for the iPhone, and along with being pretty accurate, you can click a “save” button and get one of these in your photo album. Full EXIF data for your negs from any camera! I’ve had this app for a while, but I also have a Gossen Luna Pro, so this app didn’t get much attention.
EXIF data paired with the convenience and high portability of the iPhone (it’s always with you!) and you have one of the best light meters ever!