"the site" == Lemmingsforums? Most people upload their packs to a third-party server, and then post a link.
namida recommends to ship the music separately. Reasoning: When the levels update, people shouldn't have to re-download the entire music.
IchoTolot offers his pack in two variants: A zip archive containing both the levels and the music pack, recommended for the first download, and the standalone level pack, so people can update later. Icho explains how the music is really important for the mood, and aims for a perfect first experience.
-- Simon