Give it a try: http://brieflang.com/turtle/?0(1adf89r)180x
There's also a YouTube demo here: http://www.youtube.com/watch?v=CVFcpoULWq4
It is driven by a tiny stack language allowing single-character commands to move the turtle and draw and do animations. Quotations are used to treat code as data (pushed to the stack); allowing repetition and definition of new commands.
hHome - Reset x,y to 160,160
nNorth - Reset bearing
gGo - Sets x,y from stack
cClear - Clears canvas (useful for animation)
fForward - Draws forward n pixels
mMove - Moves forward n pixels
lLeft - Turn bearing left n degrees
rRight - Turn bearing right n degrees
xRepeat - Repeats quotation n times
aAdd - Adds two numbers
-Subtract - Subtracts two numbers
*Multiply - Multiplies two numbers
vDivide - Divides two numbers
jJoin - Prepends head onto quotation
uUnjoin - Separates head from tail
dDup - Duplicates top stack value
wSwap - Swaps top two stack values
oDrop - Discards top stack value
iDip - Applies quote below next value
Parenthesis surround quotations
Digits  build decimal numbers. Commas separate adjacent numbers.
Define unused characters by following quotation.
R as substitution for
Canvas is 320x320. Turtle begins at 160,160 bearing North.