slightly off-topic, tcpdump output analysis?

[Carl Brewer <carl () bl echidna id au>]

This is a bit off-topic, but maybe someone here can help?

I'm looking at a few pretty big tcpdump output files, and
want to use them to build up a picture of the type of traffic on a network
(specifically it's a WAN link, but that doesn't matter).

Does anyone on this list have any pointers to scripts
that look at tcpdump output and build up traffic stats
etc?  Rather than write my own, I'm sure someone must have 
done this before?

thanks

Carl