One of the major conventions in UI design is to use what people already know. If you present an interface that is unfamiliar, people tend to be hesitant to accept or use it regardless of how good or bad it might be. That said, sometimes someone comes up with a new UI component that is both cool and useful. Maxime Heinault's jQuery timepickr is one such component.
Its description professes a "maximum two-click" approach to choosing a time, but if the picker opens on hover it could be brought down to one click. It's unobtrusive, degrades gracefully, is navigable via keyboard or mouse, and the button sizes are even touchscreen-friendly, for those of us in the kiosk world. The only issue I have with it so far is that it lets you type in a time, but resets itself once you tab out... It should either not let you change the value or accept what you enter.