1.Charlie Watts, Karen Carpenter, Nigel Olsson, Phil Collins: Drums
2. Elton John, Billy Joel, Robert Lamm, Little Richard: Keyboards
3. Ian Anderson, Matt Eakle, James Galway, Orlando "Maraca" Valle: Flute
4. Jerry Douglas, John Fogerty, Eric Clapton, Sally Van Meter: Dobro
5. James Pankow, Delfeayo Marsalis, Tommy Dorsey, Jason Frost: Trombone
6. David Grisman, Sam Bush, Peter Buck, Captain Corelli: Mandolin
7. Bootsy Collins, Phil Lesh, Paul McCartney, John Paul Jones: Electric bass
8. Benny Goodman, Jose Garcia, Woody Allen, Squidward: Clarinet
9. Fermin "Bongo" Goytisolo, Carlos "Patato" Valdes, Domingo "Sunny" Ortiz, Ron "Pigpen" McKernan (on stage) (I guess you need a nickname to play this instrument): Conga drums
10.Angus Young, Mark Knopfler, Steve Kimock, Billy Gibbons: Guitar
11. David Sanborn, Bill Clinton, Clarence Clemons, Junior Walker: Saxophone
12. Bob Dylan, John Lennon, Elwood Blues, Stevie Wonder: Harmonica
13. Jerry Garcia, Neil Young, Lindsey Buckingham, Bela Fleck: Banjo (gotcha!)
14. Herb Alpert, Wynton Marsalis, Al Hirt, Jesus Alemany: Trumpet
15. Weird Al Yankovic, Bruce Hornsby, Frankie Yankovic, Dick Contino: Accordion
16. Alison Krauss, Isaac Stern, Robby Steinhardt, Mik Kaminski: Violin 
17. Tito Puente, Sheila E, Amadito Valdez, the mouse in "Candela": Timbales

Bonus: King David, Emma Christian, Adolph Marx: Harp (Adolph was Harpo's real name)