I thought that i'd add my 5ยข worth on this under/overground discussion. A lot of the arguments are familiar to me from other lists and musical genres but recent experiences have thrown a new light on things - esp. the corporate experience.
I started a graduate law degree last year (after not getting far with my BA and missing uni life). One of my lecturers gave me another definition of "underground" which is a lot like what a few other people have said - ie. that the underground is the part of society which can't or won't communicate with the "mainstream, official" society. Another angle I've recently discovered which one might relate to the music industry is life as a law graduate. If you perform well enough at law school you may be selected for a clerkship and perhaps employment at one of the big firms. There you will work very hard, sometimes at all hours, on cases involving large corporations and their loot and you'll be encouraged to do so with the prospect of becoming a partner at some distant stage in the future. You will probably do this for about 10 years at which stage you would have either burnt out and left the industry or you may be one of the "lucky" few to move a step higher in the pyramid. All this time you will have been working for a set wage (a generous one perhaps relative to other jobs) with no idea at all as to what the partners are raking in. This is true, I'm discovering, of a lot of jobs in the city where you have to conform to certain patterns of social behaviour if you are to be a part of the very powerful corporate system. A lot of people are reluctant to play that game and so choose to work outside that system. These people are usually more concerned with ideals such as justice and fair play - or in the case of the music industry, music. Chris