XFCE simple Network Monitor applet
The latest and fairly improved version (now not only reports the network activity) has been moved.
Full information and screenshots in github.
The original version is also available in git history, but the new one it is as simple and easy to install:
Download xfce-hkmon.cpp and compile it:
g++ -std=c++0x -O3 -lrt xfce-hkmon.cpp -o xfce-hkmon
Place the executable somewhere (e.g. /usr/local/bin) and add a XFCE Generic Monitor Applet with these settings: no label, 1 second period, Bitstream Vera Sans Mono font (recommended) and the following command:
/usr/local/bin/xfce-hkmon NET CPU TEMP IO RAM
You may also add an interface name (eth0, ppp0,...) to override the automatic selection by traffic.