Refinements of the instrumentation and methods used for laboratory microwave spectroscopy of molecular ions in the last few years have led to successful observation of spectra of several new molecular ions of particular astrophysical interest. Notable among these enhancements have been the use of magnetic fields to increase the density of ions in discharge plasmas and the extension of upper frequency limits of the spectrometers towards and into the sub-millimeter regime. the number of ions now observed by laboratory microwave spectroscopy is more than a dozen, and about two thirds of these have also been detected, at least tentatively, by radioastronomy. Even where detections are uncertain or impossible, useful upper bounds on ion abundances can be gleaned from radioastronomical observations once exact transition frequencies and assignments are known from laboratory studies. Special attention will be given in this presentation to the status of laboratory and radioastronomical work on HOC+, H2D+, and SO+, molecular ions which have been the object of our own recent interest and effort in this area.