Every wristwatch I've ever owned has the timekeeping device on one side and the fastening mechanism on the other; that's the established form factor. But demonstrating the seriously out-of-the-box thinking they've become known for, Art Lebedev Studio's Integralus watch concept throws that out of the window.
The Integralus turns the timekeeping portion itself into the clasp, dividing the hours and minutes into discrete sections that then snap together to close the circle, both physically and metaphorically. The adjustability that's been designed out of it is then provided by offering three different-sized wristbands.
Despite the added layer of impracticality—the device requires two batteries, one for each half of the face—I totally covet one of these things. It's a simple case of design emotion trumping design logic.