Testbeds for the New Observing Technologies

They should be developed, tested, and debugged at smaller telescopes, where the observing time is more affordable

New Detectors

New wavelength regimes, e.g., mid-IR...
New array detector technologies: from Vidicons to CCDs to STJs to ...?

Image Correction Techniques

Adaptive Optics
Optical/IR Interferometry

New Kinds of Instruments

Tunable filters, integral-field spectrographs, OH-suppression spectrographs, coronographs...

What About the Ever Brighter Sky?

IR, AO, high spectral resolution, work between the night sky emission lines...