The Law of Hospitality is something that really impressed me when I came across it in some of my readings for high school. It's common to a broad range of cultures including the Dakota Indians, the old Norse, and the Bedouin tribes of Arabia. As a code, the ancient version is much stronger than what exists in modern society today.
The old code demands that a host may not turn away a guest or a stranger in need. Furthermore, to accept a guest binds the guest and the host in a contract: the host must provide his guest with food, shelter, and defense, all the best his house can offer. In return the guest should be courteous and not cause mischief.
I put Victor up for the night last night, which is what poked me to run a search on Google for "law of hospitality" so I could put a copy up on my site. I didn't find a codified version of it (so I wrote one) but I did find this. It's written by Rev. Dr. Kathlyn James and seems to be a transcript from a collection of Christian sermons. The essay stands very well on its own merits, however, so please judge it without the header. :)