Our interests lie in exploiting physical fluidic mechanisms to program and control matter at small length scales. In the first part of the talk, I will describe a novel way to employ physical computation to build all-fluidic control circuits. I will introduce how to build both "analog" and "digital" circuits that can implement universal Boolean logic, feedback, cascadability, bistability and synchronization via exploiting purely hydrodynamic nonlinearities in low-Reynolds number multi-phase flow. These circuits provide a means to control sub-nanoliter droplets in fluidic channels up to KHz regime with no moving parts. In the second part of the talk, I will describe techniques for in-situ synthesis of morphologically diverse nanostructures via geometrical control. By physically coupling growth and transport dynamics of reactants in a continuous flow reactor, we demonstrate programmed synthesis of complex geometrical patterns of Zinc Oxide nanowires in microchannels. Time permitting, I will discuss some of our on-going work on development of new tools for stretching biomolecules.