Written a few years ago, an applet which nicely draws a mandelbrot fractal (even with adjustable parameters).
You can use the left mouse button to zoom in, and the right to zoom out (click on “read more” to see the applet).

The (very simple and immature) code is attached: Mandel.java. You can use in your webpage with:

<applet codebase="http://chris.ypmamedia.nl/applets/" code="Mandel.class" width="370" height="300">
</applet>