Simple command line network monitor

From: Nathan Funk (nathan.funk_at_gmail.com)
Date: 06/23/05 

Date: 22 Jun 2005 19:57:35 -0700

I'm looking for a simple network traffic monitor that just gives me a
reading of how many kbps I have going in/out of each of my NICs.
Nothing fancy. Is there a standard command for this like "top" does for
process monitoring? If there isn't - there should be.

Thanks!

Nathan