There is only one file type that uses the .VIEWLET extension:
Interactive Flash presentation created by Qarbon presentation software; contains the Flash .SWF file, an .HTML file, and the .QVP source file, which stores images, audio files, and other resources; used for storing project assets together.
NOTE: The ".viewlet" extension actually is used for a folder and not a file. The HTML file within the folder (that references the SWF file) can be opened in any Web browser with the Flash Player plug-in installed.
Updated: October 13, 2011