If you use Facebook, please never post anything there which you care about owning (like writing samples, or especially nice photos.)
The Consumerist reports Facebook has changed their Terms of Service so that ALL RIGHTS to EVERYTHING you post there belongs to them FOREVER, even if you quit their site.
That means if you post a photo of your kid, Facebook can use or resell that photo, and there's nothing you can do about it. If you post a poem, they own all rights to it; you don't anymore. Et cetera.
Be careful of the big baddie.
Feb 18, 2009 Update: Due to widespread outrage, Facebook has back down and reverted to their original TOS. However, I would still refrain from trusting them to have your best interests in mind. I would also suggest you never post anything you care about owning (original writing, professional-quality photos) on the internet. It's hard to sell something that's available for free! :-)