George:
No, I've got several different, all complete with professional (looking) sleeves, and suitably etched 'top'sides.
Admittedly, as "Filk" they are probably from short runs of up to say 100, but a quick look at one sleeve gives a total running time of about 70 minutes.

Also, although the facilities would only be accessed by a computer user, if people knew they were available it could still be an additional feature (like Easter Eggs on DVDs)