"Optofluidics" is the marriage of optics, optoelectronics and nanophotonics with fluidics. Such integration represents a new approach for dynamic manipulation of optical properties at length scales both greater than and smaller than the wavelength of light with applications ranging from reconfigurable photonic circuits to fluidically adaptable optics to high sensitivity bio-detection currently under development. The capabilities in terms of fluidic control, mixing, miniaturization and optical property tuning afforded by micro-, nano- and electro-fluidics combined with soft lithography based fabrication provides an ideal platform upon which to build such devices. In this paper we provide a general overview of some of the important issues related to the fabrication, integration and operation of optofluidic devices and present three comprehensive application examples: nanofluidically tunable photonic crystals, optofluidic microscopy and DFB dye lasers.