Slashdot featured this CNN article on silbador, the most elaborate "whistle" language in the world. Yup, you whistle instead of talk. 4,000 words no less. Not to be missed: a recorded conversational example that goes:

Hey, Servando!
What?
Look, go tell Julio to bring the castanets.
OK.
Hey, Julio!
What?
Lili says you should go get the kids and have them bring the castanets for the party.
OK.OK.OK.

Pretty nifty!