Take a look at the $ENV{COOKIE} or $ENV{HTTP_COOKIE} scalars, they hold the crap that's coming from the browsers.

What I do is I use CGI::Cookie but it's hella slow because it loads a shitload of code (takes ~0.2s to load on my PII 266 running IIS5 and ActivePerl 5.6)

If you're looking for more client information, you'd be better off using some JavaScript code to send everything to your script in a query string, like most counters do. There's also some general stuff in %ENV but maybe others here know better ways to get kinky information form users?

Rock on,
CBAS