The classic F/1 lens is the Leica Noctilux. For those lucky enough to own one, its huge weight and price tag bought passable sharpness wide-open and creamy, buttery-smooth rendering of out-of-focus areas, worthy of any dairy metaphor you cared to heap on it.
Leica recently upped (or downed?) the ante by producing the fantastical 50mm f0.95 Noctilux. If the Leica 50mm F/1.4 ASPH is the Ferrari of fifty-millimeter lenses, the 0.95 is the Bugatti Veyron.
Link: 50mm f1.1 Nokton