From a musical perspective...
Having the ability to add either a soundcloud player, or something like that, would be really useful
as far as I know, the players are embedded .swf files, so I'm not sure what the security implications are on this one as I'm no code expert.
Also, an interactive event calendar (possibly flash or java?) would be fantastic (think google map for venue, possibly a 'preview this band' listener), they're always really good for helping both local / regional musical types and venues out; the existing feature is good, but I didn't actually spot it for a week or so despite it being right there on the front page - maybe some kind of 'newsreel' type simple animation just to attract the eye?
I'd go as far as suggesting maybe hosting some audio, but I appreciate the immense resources that this would require as audio files ain't the smallest
What do other forumites think about this idea?