Any script you throw together to output floats works. One example I have (for linux) samples wlan0 stats every two seconds to test download kbps.

The code is here: https://github.com/seenaburns/stag/blob/master/examples/netw...

Trying out some of the examples for Spark is also fun: https://github.com/holman/spark/wiki/Wicked-Cool-Usage