You can see it running a different places on the web including optometrie.ch. It has been running continuously since 1999 on different operating systems and different JVMs. It is being actively developed as I write these lines (2003) but since the latest versions are always run live on the web, the bugs are typically minor and WebForum has a very good track record at being reliable.
While the applet is not demoed live anywhere, you can browse some screenshot taken under Linux with Java plug-in from Sun :
Note : currently, a Java 2 applet which will work automatically if you are using one of these browsers : Mozilla, Konqueror, Netscape 6.0, AOL 5.0 or Opera (with Java installed). Internet Explorer and Netscape Communicator (pre 6.0) users need to use the Java plug-in. Visiting a page requiring this plug-in should send you to the proper page on Sun's web site.
© 1999, 2000, 2001, 2002, 2003 Daniel Lemire