I'm running an Ubuntu 10.04 server that hosts several domain names. All domains point to the same IP address and use the same network interface. I'm really only concerned with the main domain name such as my-domain1.com and my-domain2.com. It should include subdomains such as www.my-domain1.com with the totals for my-domain1.com. Is there a tool out there that is configurable to track bandwidth usage on a per-domain name basis?

Edit: I'm not looking for only web usage. I'm looking for all traffic.