Applying an electric field to a fluid is useful in a number of micro and nano-fluidic applications, from driving molecular separations to simple pumping by electro-osmosis. In some cases the fluid has gradients in electrical conductivity. These gradients can be introduced intentionally (as in sample stacking), unintentionally from uncontrolled sample preparation, or occur naturally upon passage of a current through an electrode. It has been known for many years that when electric fields are applied to fluids with gradients in their electrical properties that hydrodynamic instabilities can ensue. This talk will focus on a class of flow instabilities that occur in microfluidics due to the interaction of the applied electric fields and conductivity gradients. The interaction of an applied electric field and fluid conductivity gradients generates charge in the fluid bulk, the applied electric field exerts a force on the charged fluid and electrohydrodynamic motions can arise. These strongly non-linear and "turbulent-like" flows occur, despite being dominated by viscosity.