It sounds like what you want to do was discussed in a Linux Magazine Article - Getting a Handle on Traffic - in the Ocotber 2002 issue.

Basically, the idea is to save all of your log data in a mySQL database which then gives you a bunch of flexibility in reporting.

From your nick it appears you are a Debian user like myself...if so, check out libapche-dbilogger-perl which purportedly empoweres exactly what you describe.