Chiptune is a type of musical instrument or synthesizer which is generally made from hacked 80′s computer games or consoles.
cTrix has hacked an Atari 2600 using an EPROM programmer and some custom software, then combining that with some guitar pedals he’s created an instrument which he’s called the gAtari. Check out the video below for more info.
Intel have gone to the trouble of making a real life machine which plays music using balls hitting various instruments. This is apparently to promote the Intel Atom processor.
The start of the video looks like CGI, but keep watching to see the real machine.
This Star Millennium Falcon electric guitar was made from a Star Wars toy, but also has some custom parts made such as the R2-D2 headstock, and obviously the whole guitar part. It appears to play quite well and the original lights and sounds work too.
Check out the video from 1:22 onwards for some of the in progress construction pictures.
There have been several examples of playing music with stepper motors in printers and with floppy drives. Here is a particularly good example of some old hardware playing House of the Rising Sun.