Astronomers have this neat trick where they turn large celestial objects, like galaxies, into magnifying glasses that illuminate more distant objects behind them. This artist's impression, in which a remote merging galaxy is magnified, shows how it works.
I read a sci-fi novel many years ago that describes a telescope being placed in an orbit past Jupiter and which then uses our Sun as a gravitational lens. In the story, the astronomers are able to achieve enough magnification to be able to see the surfaces of planets lightyears away (even close to galactic center).
What I'd like to see is our computers being able to take the lensed light we observe and reassemble it into a picture of the light source behind the gravitational source galaxy.