The purple pitcher plant (Sarracenia purpurea) is distributed throughout the prairie provinces, eastern Canada and the eastern coast of the United States. It traps insects in rolled leaves which contain stiff hairs on the inside that point downward. Any insect that decides to explore the inside of one of these leaves never comes back out. As the dead prey decomposes, the nutrients in it are absorbed by the plant.
Butterworts (Pinguicula) and sundews (Drosera) both have some cold-hardy members of the species. The butterworts secrete a sticky substance onto their leaves, which appears shiny and may attract insects in search of water. However, the hapless bugs stick to the leaves, where the plant then secretes enzymes that digest it. The sundews have a similar tactic; with the addition of an ability to curl the sticky leaf around the insect. This maximizes the number of glands that are in contact with the prey and allows the plant to more easily secure and digest it.
The most aggressive and fascinating carnivorous plant, though, is the bladderwort (Utricularia). They have a small "bladder" that rests in the water where they live. The plant pumps water out of this trap, leaving a vacuum inside with a flexible "door" on one end. Stiff hairs protrude from the trap, and when potential prey brush against one of the hairs, the door deforms enough to break the vacuum inside; water and prey are quickly sucked in. Digestive secretions make short work of the prey while water is pumped back out to ready the trap for the next victim.
You may be able to grow one of these fascinating plants if you have a bog in your backyard, but since most of us don't, you may be able to find a similar species available as an unusual houseplant. Many cold-hardy carnivorous plants are easier to grow than the popular venus fly trap.
While many plants are grown for their edible qualities, these plants are the ones doing the eating!