The Wave plugin allows you to translate vertices to fit a standard sin wave based on user options.
EDIT: There is now a tutorial posted on the Wave page for this cartoon-fence.
This is a Windows-only plugin at the moment.
The Wave plugin is available at:
http://supercoldmilk.com/ac3dplug/wave.html
Note that the wave plugin does not add additional vertices, but works with existing ones only.
See all my plugins at
http://supercoldmilk.com/ac3dplug/index.html