I have recently come to appreciate my digital kitchen scale. It takes so much anxiety out of baking for me. I know that 1 cup of all-purpose flour = 41/2 ounces EVERY TIME! From working in the test kitchen for past 10 years, I know that flour measurement is the first place baking can go wrong (the second is oven calibration). Since my home kitchen is not as spacious as my working test kitchen, it's essential to carefully chose my "gadgets." Most digital scales are no larger than a book. Mine has a feature for ounces and grams, as well as a "tare" weight button allowing me to put a bowl or plate on the scale and get back to zero for my ingredient measurement. 

If you are considering using one, here are some standard measurements to keep handy:

all-purpose flour (4.5 ounces per cup)
bread flour (4.75 ounces per cup)
cake flour (4 ounces per cup)
whole-wheat flour (4.75 ounces per cup)