Bandwidth Monitor NG is a small and simple console-based live
bandwidth monitor for Linux, BSD, Solaris, Mac OS X and others.

Short list of features:

    * supports /proc/net/dev, netstat, getifaddr, sysctl, kstat and libstatgrab
    * unlimited number of interfaces supported
    * interfaces are added or removed dynamically from list
    * white-/blacklist of interfaces
    * output of KB/s, Kb/s, packets, errors, average, max and total sum
    * output in curses, plain console, CSV or HTML
    * configfile

WWW: http://www.gropp.org/