"Bergtatt", "Kveldsjaner", and "Scenes from William Blake's..." are the ones I would immediately recommend... "Perdition City" seems cool, but I'm not familiar enough with it to give review. There have been some advocates of Nattens Madrigal on this forum, but I, like Elisstar, am not one of them. That album, to me, almost displays parody of the poorly produced early black metal records, emphasizing their greatest shortcomings.
I even heard a story that the album was made with the intent of screwing Century Media... that after the commercially promising Kveldsjanger, they switched to that label, went out into the forest, made the record with an old 4-track recorder, and turned it in as their newest record to an angered CM... it was to be their last record with them. Of course, I have literally no idea if there is any element of truth to this story at all, but I enjoyed it nonetheless.