This work is devoted to the study of variational iteration technique and its modifications for the solution of initial and boundary value problems. The proposed modifications are made by the elegant coupling of He''s polynomials and Adomian''s polynomials in the correction functional of variational iteration method. The proposed techniques are applied without any discretization, linearization and unrealistic assumptions. It has been observed that variational iteration method and its modified versions are very efficient and reliable for the solution of nonlinear problems of physical nature. Several examples are given which reveal the efficiency and accuracy of the suggested algorithms.