Jimmy Page talks at length about how he conceptualized and produced a classic Led Zeppelin song in the Wall Street Journal, of all publications. Well worth the read.
One of the tastiest details is that the famous pre-echo on Robert Plant's voice was the result of undesired crosstalk on the mixing desk. There was no way to get rid of it, so they ended up just throwing some reverb on it and making into part of the track. Treasure those studio accidents!