Neps will eat anything that falls into the pitcher. There are documented cases of them eating mice and frogs in the wild. Snails and stuff have also been found. Pitcher plants have sweet nectar around the lip that draws all manner of insects. Mine are too small to catch roaches and house centepedes, but I have a feeling when my plant grows up it will be. Also neat fact about tropical pitchers: they have genders. Flowers are either male or female.
While we're on the topic, here are some updated pictures of my indoor pitcher plant. It's still a baby. It's seed grown, so it will take a while to reach a size that large.
Another tropical carnivore that does well on a sunny windowsill (and is quite deadly in my experience) is Drosera adelae
. Sometimes called the lance-leaf sundew (and is also commonly available at stores). I might actually have a few to give away in the springtime as mine appears to be replicating like crazy. They are also covered in bugs. Mostly small flies and mosquitoes. Here are some photos of mine since I'm not sure I've shared any.
Most people assume that because carnivores are exotic, they are also difficult to grow. In my experience that couldn't be farther from the truth. Like fish, there are some more difficult ones to keep but you don't need to keep those to enjoy the hobby.