American Sign Language, and its variations country-to-country.

What an intriguing statement. It almost sounds like ASL is the parent of all sign languages, which I'm not sure I can agree with. I have several friends who sign and they find ASL very different from both Aus and NZ SL. One major difference is the extent to which finger spelling is used. Aus and NZ SL make very limited use of finger spelling, while it seems to be quite common in ASL. Then you have something like Nicaraguan Sign Language, which is a fascinating story in its own right.