Abstract-This paper investigates the application of information-theoretic techniques to the design of advanced communication and storage systems. We use the information rate (IR), evaluated using a recently proposed efficient numerical technique, as the key parameter characterizing the system performance. As case studies, we consider three different scenarios: (i) single-carrier (SC) and multi-carrier (MC) transmission systems over linear dispersive channels, (ii) digital storage systems impaired by media noise, and (iii) optical communication systems with direct photo-detection. The obtained results show that a clever IR analysis can provide significant insights into system performance and design in several scenarios of interest in current applications.