Studies of galaxies and AGN are being revolutionised by impressive new sky surveys, such as SLOAN and 2DF, which have already significantly increased the number of known galaxies and quasars in the Universe. In the next decade and beyond, prospects for understanding AGN and their role in galaxy formation and evolution are extremely promising given the number of planned new instruments spanning the electromagnetic spectrum.
We do not yet know whether galaxies grow black holes or are seeded by them; NGST (Next Generation Space Telescope) will find the smallest black holes at the earliest times and allow us to relate them to the first galaxies and stars.
The amount of cold gas in galaxies through cosmic history is a key ingredient in star-formation, quasar activity and galaxy evolution models but is still unknown. The study of gas at high redshifts with ALMA, the GMRT and the EVLA will revolutionise our understanding its role in these important phenomena and provide powerful constraints for cosmological models.
Current models of AGN physics - fuelling, accretion discs and the acceleration of powerful radio jets - remain speculative; detailed studies of X-ray emitting gas, e.g with the highly ambitious X-ray space interferometer MAXIM, might offer valuable new insight into the energetics and physical structure of this extreme region.
Finally, the detection and detailed study of gravitational waves, using the space-based detector LISA, from massive black holes living in black-hole binary systems or in the very act of merging will prove the existence of SMBHs and perhaps provide insight into the origin of the difference between radio-loud and radio-quiet AGN.