100 More Species: #1 Woodlouse Spider
Woodlouse spider Dysdera crocata.
This male woodlouse spider hiding under the crack of our front door is a more welcome visitor than the many yellow sac spiders that come by. I don't know anyone that's been bitten by a woodlouse spider, but since their fangs are adapted to pierce the hard shells of terrestrial crustaceans, human skin probably wouldn't stop them. They seem to be very shy creatures however, preferring to hide under logs and stones with their preferred prey animals. Houses are convenient refuges for spiders, and damp conditions favor woodlice and attract woodlouse hunters.
My 365 urban species entry on this spider is one of the most heavily trafficked pages on my blog. Something about encountering a red spider (especially inside) excites the curiosity.