This week's giveaway is in the EJB and other Java EE Technologies forum. We're giving away four copies of EJB 3 in Action and have Debu Panda, Reza Rahman, Ryan Cuprak, and Michael Remijan on-line! See this thread for details.
No, you just need to install a single web server (eg. Apache, Tomcat, Resin or whatever). For each user setup a configuration file for the server and place it in his/her home directory somewhere. Then write start/stop scripts which start an instance of the software using the config from the user's own directory.