The problem I found with a Java client is that while the website is on an external server, your browser actually downloads the java applet (downloads the program) and then when you try to connect to an ssh server it's really just like running a program from your computer (that is suck behind the firewall).
If I could find a purely web-based - output in html, input in a form, it would fix this.
Is it possible in PHP to run a system command and then interact with it through a form on a website? like make the php execute "ssh $server" and then anything that is typed in the form on the website is fed to this program running on the server, and anything that is outputted from this program in shown on the website? - as that may be an easy way to do it.