This JS-based Logo works nicely: http://logo.twentygototen.org/

Here are a few programs I made with it (note that the default is to 'run normally'. You might want to click 'stop program' and then 'run fast'):

* Sierpinski triangle: http://logo.twentygototen.org/83EGZPPC

* Sierpinski carpet: http://logo.twentygototen.org/4c5iy9iU

* Sierpinski arrowhead curve: http://logo.twentygototen.org/hYDSZt8h

* Hilbert curve: http://logo.twentygototen.org/CFyUSzqG

* Hexaflake: http://logo.twentygototen.org/AJeuVkKc