In this talk we ask how sub-Nyquist sampling can be exploited in the design of communication systems and networks. We first discuss our previous work on the fundamental capacity limits of sub-Nyquist sampled channels, where we derive the optimal techniques for channel-specific and channel-independent sampler designs. We then present results on rate-distortion of sub-Nyquist sampled sources. In particular, we characterize the rate-distortion function under sub-Nyquist sampling of continuous-time Gaussian stationary and cyclo-stationary processes as a function of sampling frequency. Extensions to joint source-channel coding and network coding (routing) along with associated separation theorems are also described.