An overview of Hamiltonian systems with noncanonical Poisson structures is given. Examples of bi-Hamiltonian ODEs, PDEs, and lattice equations are presented. Numerical integrators using generating functions, Hamiltonian splitting, symplectic Runge-Kutta methods are discussed for Lie-Poisson. systems and Hamiltonian systems with a general Poisson structure. Nambu-Poisson systems and the discrete gradient methods are also presented. (C) 2005 Elsevier Ltd. All rights reserved.