Nicaraguan Sign Language is a new language that was developed by deaf children in Nicaragua after the revolution. They were sent to a school where the teachers tried and failed to teach them a simple sign language based on Spanish with very simple hand signs. The children rebelled (yay! go kids!) and did not show interest in having this language forced on them. Instead, they developed their own language in the playground, in the bus and after school. It is a full language, and new cohorts of children kept expanding the language and making it more expressive. Now it is considered a new and full language. Roxors.

Check out:

Signwriting.org
Nicarguan Sign Language Programs, Inc.
A five minute PBS video about NSL.