Post-rock, in a nutshell, is taking all sorts of music that were not meant for rock instrumentation and, well, add to it rock instrumentation. I know it sounds rather baffling, and quite trivial, but I assure you: the results I've seen such a mangling produces are out of this world.
Take for instance Mooncake: Yuan won't let me lie to you guys: a band consisting of two guitars, a cello and drums isn't exactly what Virgin is looking for, but the moment you listen to stuff like Rain in the Ashtray you're sent spiraling down into musical bliss.
There's also Mono (don't be frightened by the apparent ambiguity of that link) and their album Hymn to the Immortal Wind. There's so much emotion spilled into that album that you're left wondering where is it that you can get moar.
In other news, Susan Calloway sang for a second time Memoro de la Ŝtono - Distant Worlds. The poor quality video that a fan uploaded (whom I want to track down and kill because I'm an envious little twat) is the only evidence of this jewel. Let's be honest: Susan's version of "Distant Worlds" is way, way, way better that every other version of the song, including Izumi Masuda's. I'm left wondering how is it that Susan isn't really that famous...