A prospective job was asking applicant to visually explain what happens during "network crosstalk" without using text.
The 2 difficult things I had with this was doing 3D with Flash and finding a corny soundtrack.
<object width="550" height="400">
<param name="movie" value="Crosstalk.swf">
<embed src="http://i105.photobucket.com/albums/m214/bushwhip/Crosstalk.swf " width="550" height="400">
</embed>
</object>