The aforementioned Amazing Mr Smith has made a variety of instruments from condoms. Have a look at his web page.

Jonathon Shorland (among others) has a set of bagpipes he made from a rubber glove, a camping foot pump and various bits of hosepipe.

For my sins, I can play Turkey in the Straw in a plectrum - same principal as a Jew's harp - try it.

A couple of years ago, Techniquest in Cardiff organised a series of concerts with the National Orchestra of Wales, featuring a newly commissioned work in which several strange instruments were played, including a giant swanee flute made from an adapted bass recorder, a bumfiddle - a one string fiddle with an inflated balloon as a resonator (it looks like a bum!) - and a variation on the glass harmonica in which lights were activated by the different notes.