Most people know that daffodil bulbs will "naturalize," meaning that they will multiply in the ground, each bulb adding one or two more each year. But there is another way to increase your bulbs--a process called scaling in which you slice the bulb into sections that will then form bulblets. Bulbs produced through scaling will take two or three years to flower, but you can potentially produce more bulbs through scaling than through naturalizing.
To scale a bulb, begin by clipping off the roots, taking care not to damage the bottom of the bulb, which is called the basal plate. Using a sharp paring knife, cut off the stem tips of the bulb. Then, starting your cuts at the basal plate, cut the bulb into sections lengthwise. Depending on the size of the bulb (I'm using the small tete-a-tete daffodil bulbs here), you can usually cut them into quarters or eighths. Make sure that each piece has some of the basal plate attached. If the basal plate becomes detached, throw out that piece--it won't form bulblets without it.
Pull out the center part of the bulb section--this is the actual flower stem and it will be discarded. Then, using the knife, separate the remaining part of each bulb section into two-scale sections, each with a piece of basal plate attached. If the scales are so thin that you can't separate all of them, that's probably OK, but you want to get as many two-scale sections as you can. The bulblets will grow between the two layers of scales.
Put the scales into a Ziploc bag filled with moist vermiculite. Gently distribute the vermiculite around the scales so that they're well-covered. Seal the bag and put it somewhere warm. You'll need to check it every so often for rot--if any of the scales look funky, discard them. The bulblets should form in about 8 to 10 weeks. The bulblets can then be potted up with each scale tip just above the surface. The bulbs should leaf out the following spring, but will need another year or two to flower.