I ordered two pictures from HauntedMemories.com and I hope to have them framed and placed at strategical points in our flat where they'll do maximum psychological damage to unsuspecting visitors.
You see, the images, when viewed from front, seem like normal ancient portraits. However, If you move to either side, they change to something rather unpleasant. Of course this trick is old (I remember Czech postacrds like this from the early 1970s) but these paintings are done very profesionally and the change is gradual (several stages and even something that looks like animation (see the actual footage here).
I purchased "Da Vince Corpse" and "Uncle Charles" (smaller versions) for $140 total, including $20 postage to the Czech Republic (which includes package insurance).
Surprisingly, even Karolina "sort of" likes them and came up with the idea of buying the aunt for the uncle. We shall see...
If you have enough space (and money), I definitely recommend going for the large versions, the detail is really amazing.
UPDATE: I almost forgot: If you are really rich, for "at least $800" the author offers to create a custom changing portrait based on your photo! See the FAQ on his pages.