Just for the record, the Jew's Harp is a class of idiophonic Linguaphone, rather than a free reed instrument, which are in any case aerophones rather than idiophones. On certain Jew's Harps (the Indian heteroglottal moorsing for example, and certain of the dan moi type idioglots) it is possible to resonate the tongue by means of the breath alone, generally on the suck, but all this gives you is one sustained tone.

Other Linguaphones are the thumb-piano (mbira, sansa, kalimba etc.) and the Fender Rhodes.

Anhow, here's the Wikipedia list of National Instruments, which makes for a fascinating read, and enlightens us as to what England's National Musical Instrument actually is!

http://en.wikipedia.org/wiki/National_instrument