Paint isn't the only way to perk up built-ins and furniture with color. Hardware can add a kick too, whether as an alternative to a full-scale paint makeover or as the finishing touch to one. Not sure which hues to choose? A foolproof approach is to go for a knob that echoes the color of the cabinets—including yellow-, red-, or brown-toned woods—for a unified look. Or choose a complementary scheme for a little more zing. Here and on the following pages, 21 of our favorite bright ideas.