I screen my calls, too, but the ones at 5 in the morning still wake me up...
The pages says that it's illegal to send faxes without written permission starting July 1, 2005, but that just strengthens the already existing rules. I called them, they said it is already illegal to send unsolicited faxes, and they have a form you can fill out and send it to the FCC. They do go after them.
I was getting several faxes a day, but they really did stop them.
http://www.fcc.gov/cgb/consumerfacts/unwantedfaxes.html
"I screen my calls, too, but the ones at 5 in the morning still wake me up..."
Turn the ringer off before you go to bed. That way they can still leave a message if it is important, but won't wake you otherwise.