Isotachs

http://www.erh.noaa.gov/btv/events/28Oct2008/ua2.php

Isotachs are very similar to isobars in that they use lines to connect areas of equality.  In the case of isotachs instead of measuring atmospheric pressure it measures wind speeds.  These maps are useful in hurricane analysis.  The map above shows not only wind speed using isotachs but also wind direction.