The advances in bolometric detector technology during the last 15 years have allowed (sub)millimetre wavelength measurements to contribute important data to some of the most challenging questions in observational cosmology. The availability of large-format filled-array cameras during the next decade, however, promises to provide FIR to millimetre observations with unprecedented imaging fidelity. The simultaneous increase in the telescope collecting-area of new facilities will also provide the observational data with greater sensitivity and resolution. In this brief review I highlight the major results from the first 6 years of (sub)millimetre extragalactic surveys, in particular those that have offered constraints on the evolutionary history of high-redshift AGN and optically-obscured dusty starburst galaxies. I also illustrate some of the difficulties and ambiguities that arise in the interpretation of the existing submillimetre data and their follow-up multi-wavelength observations. Finally I describe why, with the combined optical and IR capabilities of the GTC and the future FIR to millimetre wavelength experiments (BLAST and the LMT), we can shortly expect to answer the outstanding questions regarding the nature, redshift distribution, luminosity function and large-scale distribution of the (sub)millimetre population of galaxies identified in blank-field surveys. The careful coordination of GTC and LMT surveys (via a key project) will significantly contribute to the scientific return of both facilties.