I have written a little panel applet for the GNOME Panel that shows your current network traffic in plain text. You can choose one or more of your network interfaces and a adequate speed unit, as you desire.
Here a screenshot:
A tarball can be downloaded here: download
The CVS source code can be browsed here.
It’s being released under the GPL, so feel free to change and redistribute.
Please test, comment,enhance, redistribute … 