Spoka: The Spoka is one of my favorite affordable nightlights, much like many of IKEA's goods. It comes in two different character shapes. Each Spoka changes color. One goes from blue to green, the other from red to purple. The pulsing of the light has a soothing effect that can help kids go to sleep.
Giraffe Night Light: I love the size of this nightlight because it adds a nice touch both when sitting on a table and on the floor. There's something comforting about having animal shaped nightlights. If you're not into giraffes so much, there is also an elephant version. Both lights have an on/off toggle switch with a polarized plug and use low-energy fluorescent lighting. The animals are made of constructed die-cut, hard-formed sheets.
Gummy Bear Light: Gummy bears are my favorite candy and I almost want this nightlight for myself. These nightlights come in orange, red, green, yellow or clear and are lit by pressing the belly. They run on AA batteries and can either sit by the bed or be mounted to the wall.
Bird or Teacup Light: Finding lighting appropriate for kids doesn't mean the night light or lamp has to be overly cute. Anthropologie has a couple lamps that are whimsical enough for both adult and children's rooms. My favorites are the teacup stack and the birds.
Large Mushroom Lamp: If your child is a huge fan of fairytales, this toadstool lamp will be perfect for your little one. The large mushroom gives off a cozy, comforting glow. (Images: As credited above.)