Microfluidic systems are now being designed with precision to execute increasingly complex tasks. However, their operation often requires numerous external control devices due to the typically linear nature of microscale flows, which has hampered the development of integrated control mechanisms. In this talk, I address this difficulty by demonstrating how microfluidic networks can be designed to exhibit a nonlinear relation between applied pressure and flow rate, which can be harnessed to switch the direction of internal flows, induce spontaneous oscillations, and give rise to multistable flow states. I will show how these dynamics arise from nonlinear fluid inertia effects in laminar flows that can be amplified through the design of the network geometry and thus do not rely on external control systems. These results are supported by a combination of analytic models, simulations, and experiments, and I hope will convey a new approach to designing programmable microfluidic systems.