I name the symbolic link as their short user name. When they want to access their personal web site, they only have to type http://mydomain.com/user/. For those of you wanting to know how to make the link, just open a Terminal and type:
% ln -s /Users/username/Sites /Library/WebServer/Documents/usernameReplace 'username' with the user's short user name, obviously. That's all you need to do; the users can now access their sites without typing the tilde. My users like it, so I thought maybe one of you may find it useful.

