In terms of 20th century recordings, The Beatles' Sgt. Pepper's Lonely Hearts Club Band was maybe the most revolutionary, innovative recording of its time. I believe they only had 8 or 12 tracks to work with, amazing considering all the orchestral elements of the recording. Also, they used a number of alternative mic techniques, effects, and equalization tricks. Producer George Martin has said that virtually nothing was recorded the usual way. Perhaps most unusual of all for that time, they sliced and diced the tapes, splicing them together in odd ways, setting a trend which many others have since explored...you probably could make a case for this technique setting the stage for current computer eletronica compositions, or even ProTools recording technology. One of the first albums with a gatefold sleeve, it also was one of the first albums to feature printed lyrics in the cover art....a revolution in album design as well as recording technique. There is plenty of documentation about all this, and with all the pop culture tie-ins I'm sure there's enough to get a 20-page paper out of it.