Well, primarily for the discussion of music. However, this being RedMarx, we think we could afford to go a little bit further than that. As such, we would be especially interested in discussion from a more analytical perspective, looking at why certain songs and artists have a particular effect on the listener; what techniques they use, how they create atmosphere, what effect their lyrics have, etc. This needn't mean posting a dissertation, if probably more than a one-liner, but should generally not be that hard in discussing a band which one likes; what they do, how they do it, and so on. You can also speak, of course, of a band's deficiencies, although we would prefer this also be elaborated, and as such we would rather you post your disapproval of a band which you think have some good ideas and intentions but a flawed execution, say, rather than one which you simply despise wholesale. We also wouldn't mind speaking of musical theory and its relation to musical practice, as well as the history of musical genres and so on.
However, for your less serious posting needs, you can try out the official and unofficial genre threads, such as the Official RedMarx Heavy Metal Thread, where we generally allow free discussion, the posting of Youtube videos relevant to the genre, etc. In addition, these threads may introduce 'themed weeks', in which posts within a certain week follow a given theme in order to co-ordinate discussion, such as focusing on black or progressive metal, or having a conversation carried out through posting Youtube videos of songs. We shall also be generally permitting towards threads begun in order to discuss upcoming releases, as there won't necessarily be any music to analyse per se in such threads. Of course, don't feel like all of your posts elsewhere have to be long and detailed, and you can, for example, give a short elaboration on somebody else's point or say that you like a band for reasons which they have suggested, but we would prefer if the former kind of posts formed the central crux of discussion.
"The thing [calculus] has taken such a hold of me that it not only goes round my head all day, but last week in a dream I gave a chap my shirt-buttons to differentiate, and he ran off with them."
- Friedrich Engels.
Vocatus atque non vocatus Deus aderit.