This tutorial shows how to utilize reflectors to get some light into small spaces.
The video above shows how a commercial got around not being able to light in a tight cave space (with a toilet!). But one instance I can remember of this being used for a film production was 2005's "Cache".
Cinematographer Christian Berger lit some scenes with one light, and carefully places mirrors all over the entire set reflecting the one source light in various ways. So each mirror essentially became a light source.
Come to think that's a brilliant idea, both saving energy and space for actors to move around. But it would probably take a lot of planning ahead of time, as well as fitting clamps and such to accommodate mirrors.
Hurry Up and Wait Link: http://goo.gl/kSNPsg