Try it here!
According to Wikipedia, A fractal is generally "a rough or fragmented geometric shape that can be split into parts, each of which is (at least approximately) a reduced-size copy of the whole,"[1] a property called self-similarity.
Recently I added a post about a Silverlight application to draw Koch Curves. I re-programmed it in PHP using the PHP GD image library. The output is a Jpeg and can be saved like a normal image. You can try the application by clicking on the sample image. The only input you need to provide is the number of iterations (levels) which can be selected from the given dropdown.
You can also download the PHP code from phpclasses.org. Click on the sample image to try it yourself.