The "write[]" functions in both Decker and Lilt can save image interfaces as .GIF images (including transparency and animation, if desired), and it can save sound interfaces as 8khz monophonic .WAV files.
The GIF files emitted by Lilt/Decker tend to be quite large, as they make no effort to compress their image data, so it may be desirable to use ImageMagick, Gifsicle, or a similar GIF optimizer to process their output.
It's also possible to write out arbitrary binary files by using an Array interface, but this is more involved.