In the old days, you could get bonus software for your Sinclair Spectrum PC encoded as audio on vinyl record albums. This exhaustive, loving report has links to the code and emulators for executing it.
In the case of these programs on vinyl, the user would have to play back the proper portion of the record, record the resultant chatter to tape, and load the tape into the spectrum. Some users have mentioned playing certain games so much that they could recognise the loading sounds.
(Thanks, Jed!)
