One other interesting idea from Magnatune was to allow customers to download the album immediately if they had ordered a physical CD.
This had the plus of capturing those that wanted "instant" access to the music.

This brings up another difference with folkies, and perhaps this is just my impression, but most folkies I know are UNlikely to be using ipods etc extensively and ARE more likely to be ok about waiting for the postman to arrive with their new CD!

Per track download, I agree, are likely to be unpopular for folk music.