Splitting eth0 traffic into two virtual interface

Hello everybody,
I have been reading many posts about this topic but I have no figure out how to solve it.

I need to split the traffic incoming on eth0 on two other interfaces (for instance one receiving on port 80 and the others on the other interface).

I cannot understand how to do that. I created bridge but it cannot receive traffic..
I know about ip route 2 but I need to give a interface name to a software of monitoring.. so I cannot just create childs..

How can I do?

Thanks a lot for your help
I would appreciate
Nick

What's your system?

Ubuntu 10.10

but I would like to be able to do it even on Centos6