An electron ionizing a simple atom or molecule on one hand is a very fundamental few-body problem and on the other hand this reaction is important in our environment and in applications like plasma physics and radiation therapy. The most detailed insight into the scattering dynamics is provided by the measurement of the momentum vectors of all particles involved. After an introduction some of our recent studies are presented like ionization of aligned H2 molecules and of small clusters from noble gas, the fragmentation of bio-molecules and collisions involving positron projectiles.