  We review Lipatov's high energy effective action and show that it is a useful
computational tool to calculate scattering amplitudes in (quasi)-multi-Regge
kinematics. We explain in some detail our recent work where a novel
regularization and subtraction procedure has been proposed that allows to
extend the use of this effective action beyond tree level. Two examples are
calculated at next-to-leading order: forward jet vertices and the gluon Regge
trajectory.
