If you still have some ATAPI-interface CDROM drives kicking around from the late 1990s - don't throw them out, as they can be used as simple audio CD players. The people at single valve have created a circuit that interfaces an Arduino board via some I2C port exapnders to control the drive, and also retrieve playback information. A natural extension to this is adding infra-red remote control, which is simple to achieve using the library and an IR receiver module.
To take this one step further, an LCD module could also be used to display the playback information and times. So the next time you see an old desktop PC awaiting council cleanup - consider picking it up and making a CD player out of it.