Logo worked for me. If you want to teach a "real" language (Logo is practically a LISP! It's real!) then Python has a turtle module.
Another Logo fan here. I still haven't found any other environment that makes me wonder about the power of computers as Logo did. I was 7 to 10 years.
Cory Doctorow called Squeak "logo for the 21st century."
http://squeak.org/