Here's some more ifs files for you to play with:

coral.ifs
crystal.ifs
examprob1.ifs
flower.ifs
fractalmaze.ifs
hw.ifs
sierpinski.ifs
spiral.ifs
swirl.ifs
tree.ifs
tree2.ifs
zigzag.ifs

Challenge problems: Make the ifs files for the Sierpinski gasket (not tilted), Koch's snowflake, and the image below: