The strong coupling between chemistry or electrochemistry and mechanics at interfaces may be exploited for designing materials with unexpected functional behavior. One example is provided by nanoporous-metal based hybrid materials that behave similar to piezoelectric ceramics: Bodies of nanoporous gold impregnated with electrolyte emit exceptionally robust electric signals when subjected to external load. The metal-based material may thus be considered as piezoelectric, in a literal interpretation of the term. Another example is a class of novel phenomena in which the mechanical response to load – which may be elastic or plastic – can be tuned by an electric potential. The relevant capillary parameters can be either, surface stress or surface tension. In each case, a coupling between the capillarity and electricity is crucial, and the coupling strengths can be quite different. While the energy-charge coupling at a surface is described by the Lippmann equation, a predictive understanding of the interfacial stress-charge coupling, which governs the apparent piezoelectricity, remains elusive. The talk will discuss relevant issues from the perspectives of experiment, phenomenological thermodynamics, and atomistics.