We present photonic crystal structures that exhibit small group velocity of light, which can be used as compact optical delay component. We experimentally measure the group velocity reduction to be less than 0.008c. By breaking the rotation symmetry of the structure we also use them to control the polarization of light. Finally, we demonstrate a new type of laser by fabricating array of coupled photonic crystal nanocavities in active medium, which improves differential quantum efficiency and laser output power. In our experiment, we observe a single mode lasing and measure the output powers that are two orders of magnitude higher than in single nanocavity lasers.