I have not heard a lot about ways to facilitate user sessions without having to resort to storing something on the client's PC. Say, normally a unique identifier is stored in a cookie in order to trace clients to session data on the server. An alternative to using cookies, you could explore other schemes of tracking users across the stateless protocol (HTTP) which literally runs the 'web'. This is to make use of your clients IP addresses. However, I would not advise this as a very 'solid' option.
There are already a lot of Perl modules that were designed to help you in cases where you need to maintain a persistant client state (as in a session). Take a look at
Apache::Session for example. Or,
CGI::Session. Also, use
CGI to retrieve form parameters and do other.. err.. CGI related stuff ;)
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