I developed a very nice method to measure the entanglement of pure states
Renan Cabrera, Herschel Rabitz, The landscape of quantum transitions driven by single-qubit unitary transformations with implications for entanglement, J. Phys. A: Math. Theor. 42 (2009) 275303.
This method is based in the measurement of the Bures distance between a given state and the closest separable state, which allows one to calculate the generalized Schmidt state. The entanglement can be measured from the coefficients of this Schmidt state.