The self-released One Quiet Moment by Polyfuse (aka Justin McGrath) begins as a tenuous, ever so slowly throbbing sine wave. The sound is about as thick as your arm and long enough to wrap around a tractor trailer several times. Over time, just about 18 minutes in all, it moves from frazzled FM noise with an underlying pulse, to humorously oscillating fuzz, to fritzy layers of extrapolated sound aura, to deep bottom-scraping loads of undulation (MP3).
The individual segments are intoxicating, and the real pleasure is in hearing the way the transitions are made. More info at polyfuse.net.