In this work a selection of papers dealing with NMR indirect spin-spin coupling constants published between 1999 and May 2003 are reviewed. Care is taken to avoid overlap between this work and several important review articles published during this period. A general introduction is followed by two main sections. In the first section, the most relevant advances in theoretical approaches to calculate and analyze these spectral parameters are discussed. The relevant role played by both non-relativistic and relativistic DFT-based approaches is highlighted. In the second section, calculations, analyses and measurements of couplings in molecular systems providing an interesting insight into how intra- and intermolecular interactions affect spin-spin couplings are discussed. Special attention is given to couplings transmitted through a hydrogen-bond, a phenomenon that proved to be very important for studying important aspects of structural molecular biology. Other interactions are also discussed, such as the through-space transmission, proximity effects, factors that define the stereo-specific behaviour of several types of couplings, medium effects and nuclear motion effects. Instead of aiming at an exhaustive analysis of the current bibliography, priority is given to comments that convey both the idea of the enormous potential that indirect spin-spin couplings have for studying molecular processes as well as their usefulness as probes to study subtle aspects of electronic molecular structure.