That makes me remember way back as an intern when I turned our testing tool into a crude music player by using a table of note frequencies and a text file format based on sheet music to make Chopin's Etudes play over the PC speaker by calling Beep().
Some people might remember from really old DOS games, but... You can even use the PC speaker as a "soundcard" (Actually as a 1-bit DAC. Here's the function called a few thousand times per second when using the Linux audio subsystem, updating the 1-bit output to the speaker (timer control of this output is disabled in this operation mode, kernel config is CONFIG_SND_PCSP).
There was this one game I picked up off the shelf at Target wayyyyyyyy back in the day (likely around 1990-1992) that had printed on the box a selling point that you could hear music without a sound card. It used the pc speaker. And sounded horrendous.
Still can't remember what the name of the game was and had been trying to track it down the last few years to see if it was as bad as I remembered.
I just remember high color (S?)VGA rendered/scanned in graphics, a man who was visiting alien planets and battling monsters. My 386 at the time was too underpowered to make the game remotely playable.
It was also possible to record by sampling one of the parallel port pins. Lousy sound quality, but we manged to record a song and play it back over the speaker, and have it be recognizable.
Great suggestion, but a little late. :) At 19, no EE experience, and only a few months of experience with C, we barely knew what we were doing. We also managed to fry one computer by turning up the amplifier too high.
