Even now, years after many of the missions, these space datasets could stand serious look-throughs. Patient amateurs, unbothered by imminent grant proposal deadlines, could really excel at this. There are whole astronomical data centers that do this, too. This provides catalogs of all manner of astronomical objects, whether stars, galaxies, or whatever else. Like him, many amateur radio astronomers build their own instruments, both simple and complex.
Most amateurs observe in the optical, though.
NOAO therefore deserves mention, partly because of IRAF, its free software for CCD imaging. Solar max was especially good at observing solar flares. Unfortunately, since anyone can send e-mail these days, so is the number of false alarms. In both, professional observers organize amateur observing campaigns. These often produce useful science if done carefully, even with modest equipment.