I've always liked this one from Jim O'Rourke because of it's disturbing awesomeness. It's a great record to listen to when you have company over because it is chill, it's got a nice arc to it and it is topical with songs like "Women of the World"... but then your guests see the album art sitting out and are either freaked out or intrigued. Those that are intrigued make for far better guests :)
What about you? What's your favorite album art? Post an image if you can.