Dispersions of micron-sized colloidal particles are relevant for
applications (ink, paint, etc) but are also ideal model systems
for classical statistical mechanics in order to understand
phase transitions (liquid-solid, fluid-fluid demixing, glass formation).
By applying an external field (e.g. electric or magnetic field)
one can tailor the interactions between the particles and bring
them into nonequilibrium in a controlled way. This leads to novel
emerging behaviour. After an introduction the following examples
will be discussed: lane and band formation in driven binary systems,
hydrodynamic instabilities on the particle scale, and the complex
structure formation in suddenly quenched dispersions.