I came across this site a year or so ago and really enjoyed using it to discover and draw various well-known fractals.
Here are a few programs I made with it. For some reason I tried to write them in a pure-ish functional style, accepting that the turtle has to move and turn but avoiding the "cheat" commands like setxy (placing the turtle at an absolute position) or make (setting a variable). Note that the default is to 'run normally'. You might want to click 'stop program' and then 'run fast'.
Here are a few programs I made with it. For some reason I tried to write them in a pure-ish functional style, accepting that the turtle has to move and turn but avoiding the "cheat" commands like setxy (placing the turtle at an absolute position) or make (setting a variable). 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