Time to seek the wisdom of the Perl Monks again...

I'm trying to write a CGI script that will turn a directory into a tar.gz archive, then return that archive to the user. The problem is, I probably later won't have the disk space to make a temporary file; is there a way I can send the output of tar directly to the browser without buffering?

Also, is there a way to modify the CGI headers such that when the browser pops up the "Save As..." dialog, the default filename is something like "backup.tar.gz" instead of "backup.cgi"?