Note: For QGIS3+ use the VectorFieldLayerManager

Renders a point layer with arrows representing vectors. The
size and orientation of the arrow is data defined. Typically this
would be used to represent movement, fluid flow or ground deformation
for example. The plugin can also draw an ellipse representing the
error covariance of the vector. The scale of the arrows can be easily
changed using buttons on the toolbar. The plugin can also
draw a scale box on the map showing the magnitude of vectors.