I have added the following roles / credits to the ever expanding credit list at http://help.discogs.com/wiki/SubmissionGuidelinesCreditList
Shenai – Indian reed instrument
Bandoneon – a free-reed instrument particularly popular in Argentina
Autoharp – a zither-like musical string instrument having a series of chord bars attached to dampers which, when depressed, mute all the strings other than those that form the desired chord
Vibraslap – a percussion instrument consisting of a piece of stiff wire (bent in a handle-like shape) connecting a wood ball to a block of wood with metal “teeth” inside
Kazoo – a simple musical instrument (membranophone) that adds a “buzzing” timbral quality to a player’s voice when one hums into it.
Arco Bass- an acoustic bass guitar redesigned to be played upright.
Gong – a wide variety of metal percussion instruments.
Shaker – A shaker may comprise a container, partially full of small loose objects such as beads, which create the percussive sounds as they collide with each other, the inside surface, or other fixed objects inside the container
Suling – an Indonesian/Philippine flute made out of bamboo used in gamelan ensembles
Bansuri – an Indian side-blown flute made of bamboo or reed with six or seven holes
Bullroarer – a longish piece of cord fixed to an oval piece of wood or other suitable material which usually is thicker in the center, and sharpish at the edges.
Veena – a plucked stringed instrument used in Indian classical music from Southern India
Leader – Also Band Leader or Orchestra Leader, the head of a group, orchestra, or other music ensemble who often takes on tasks such as organization, musical arangement, hiring and firing musicians, musical direction, and other group based tasks.
Bodhrán – A frame drum ranging in anywhere from 10″ to 26″ in diameter, with most drums measuring from 14″ to 18″. The sides of the drum are 3 1/2″ to 8″ deep. A skin head is tacked to one side.
Psaltery – A stringed musical instrument of the harp or the zither family.
Tárogató – a single reed instrument. It is made out of wood and has a conical bore, similar to the soprano saxophone.
Janggu – Also called janggo or changgo. A percussion instrument used in most kinds of Korean traditional music. It is made from a hollow wooden body and two leather skins. The two sides produce sounds of different pitch and tone.
Ching – A small bowl-shaped finger cymbals of thick and heavy bronze, with a broad rim commonly used in Cambodia and Thailand.
Buk – a traditional Korean drum. It is barrel-shaped, with a round wooden body covered on both ends with animal skin.
K’kwaengwari – metal idiophone.
Omnichord – An electronic musical instrument manufactured by the Suzuki Musical Instrument Corporation. It typically features a touch plate and numerous chord buttons.
Kalimba – Also called Thumb Piano, Finger Harp, Mbira, Kissansi, Sansa. An African plucked idiophone.
Singing Bowl – also known as a Himalayan bowl or cup gong. The instrument is made of metal, played by hitting, striking, or slowly rubbing/stirring a wooden striker/mallet within or on the top outer surface of the bowl