A very simple Java applet/servlet combination that lets people paint small images in an applet window, and then upload them (as GIFs) to the server.
The applet uses Jef Poskanzer's code for encoding images (GIFs).
The server uses some JSP code, running under Tomcat, which is invoked transparently from Apache via mod_jk. If you want to customize it for your own site you probably need to adjust the URLs in the .jsp and the .shtml files. The applet .jar should work as it is without patching or recompilation. But don't forget to set write permission on the upload directory for the userid that runs Tomcat (you do run Tomcat as "www", "apache", or "nobody" but never as "root", right?)
Example page. You'll need a browser with Java 1.1 or later to play with the applet.
Source code for the applet and the JSP services.