I hear requests by users all the time for the manufacturers of building components to provide their CAD library's Revit ready and this is slowly starting to happen. The latest firm to add to this growing list is Armstrong Ceilings. Although at the moment this is US and Canadian centric, it's not a big deal to convert them for metric use.
Each sample includes all the manufacturers property parameters for the specification of the ceiling tile which is extremely useful. A jpeg image is also provided so that you get a accurate representation of the ceiling when rendering.
More details can be found here:-