Some decks seem to do it automatically. My Toshiba 5-disc changer handles the region 0 PAL discs with no problem, full color video and stereo sound are perfect. My Panasonic, on the other hand, switches everything to black and white, and there's a framing issue as well a sort of strobing effect...
The Tripods was released region 0. There are several UK houses that typically do that - Revelation Films, Network, and Acorn UK come to mind immediately. Some Australian companies do the same. Enough of them do it that I sometimes forget not all of my players are region-free. :>
I got my first region-free DVD player about 5 years ago. That one died, and I've since gotten two more. I get DVDs from the US (and Canada), UK, Australia, Russia, France, and Japan. I'm in debt up to my ears with TV on DVD sets and individual discs numbering well over 100 - probably 200 or...