iftop is a really cool util to monitor your network with and you can get a lot info on a near live basis. Here is one of the uses I have for it when checking on DSL traffic.
iftop -P -i eth0 -f "not host 10.1.1.11 and not host 10.1.1.8 and not net 10.1.0.0/24"
which basically will get you all traffic on eth0 except where the source or destination host is not 10.1.1.11 or 10.1.1.8 and the subnet is not 10.1.0.0/24 (helpful on multihomed servers).
Enjoy