This little guy appeared briefly on our front porch. I'm assuming it's some sort of caterpillar.
Update: Zac managed to figure out that this is a Papilio troilus larva and will become a Spicebush Swallowtail butterfly. It uses mimicry as a defense, and, according to Wikipedia, is brown to look like poop, so it doesn't get eaten. I still think it's adorable.