LunarG also provided an SDK which comes with various tools for debugging, validation, shader generation/compilation and various other uses: http://lunarg.com/vulkan-sdk/
EDIT: Nvidia has day one support although they released two different drivers the same day. The drivers on this page contain a Vulkan ICD: https://developer.nvidia.com/vulkan-driver
All upcoming drivers should support Vulkan out of the box.
The author of one of the graphics libraries I use has been keeping an eye on it, and is now planning to start implementing support. It will be interesting to see where this goes.
Please note that this initial Windows driver is not packaged with DirectX® driver components, so it is not a suitable replacement for your everyday graphics driver.
NVidia also has beta drivers, but I don't think they have the same issue as AMD's.
Downside is, you need a 6xx/newer card.