Digital kitchen scale
It would be cruel to plug Ratio without also mentioning kitchen scales. If you don't yet have a digital kitchen scale, get one. It's that simple. You'll be amazed at how often you use it. We use the Escali Primo Digital Multifunctional Scale [$24.95] and have had no issues. It can handle up to 11 pounds, has options for metric and imperial and has a tare button for easy measuring. It even comes in seven different colors if you're the type that has to have everything match.
Some of our upcoming recipes will feature weight measurements, so be sure you're on the same page.